Mangled bodies were shown in pools of blood outside rows of shattered buildings and piles of rubble strewn across a broad avenue.
State television called the bombings, the first in Aleppo since the uprising against President Bashar al-Assad's regime erupted almost a year ago, the work of "armed terrorist gangs."
It said a "suicide bomber in a car packed with explosives" had attacked a police station, flattening a nearby food distribution centre. The second targeted an intelligence base.
The rebel Free Syrian Army blamed the government itself for the attacks.
"This criminal regime is... carrying out bomb attacks in Aleppo to steer attention away from what it is doing in Homs, Zabadani and elsewhere," its spokesman, Colonel Maher Nouaimi, told AFP in a telephone interview.
State television showed emergency workers holding body parts, including hands, feet and a torso. Soldiers were among the casualties, it said.
"The number of casualties from the two car bombs in Aleppo has risen to 28 dead and 235 wounded," said the health ministry. Among the dead were soldiers and civilians, including children.
The Syrian Observatory for Human Rights said at least 30 people were killed in the Aleppo blasts.
Several people interviewed on television denounced Turkey and Qatar for not standing by the regime as it seeks to put down the revolt.
"Is this the freedom they want?" asked one angry looking man, holding up a severed arm and referring to those leading the protest movement.
Syria blamed the blasts on "terrorists" backed by Arab and Western nations, in a letter sent to the UN secretary general, the UN Security Council, the Arab League and other organisations.
"Certain countries in the region are behind a propaganda campaign against Syria and are harbouring armed terrorists for so-called humanitarian reasons," it wrote, the official SANA state news agency reported.
Aleppo has been largely spared the unrest that has rocked the country since mid-March and killed more than 6,000 people, say rights groups.
In central Syria, tanks stormed the Inshaat district in Homs overnight as troops launched a house-to-house sweep to crush regime opponents, the Observatory's Rami Abdel Rahman said.
Inshaat is next to Baba Amr district, which has been subjected to a withering assault by regime forces since Saturday that has killed more than 450 people, activists say.
In addition to the victims of the attacks in Aleppo, the Observatory said another 44 people were killed across Syria on Friday -- 28 civilians, nine soldiers and seven deserters.
Security forces deployed heavily outside mosques nationwide, firing on worshippers in some areas to prevent protests denouncing Russia's steadfast support for the Assad regime, activists said.
"Demonstrations broke out in various parts of the country, but they were small in numbers because of the heavy deployment of army and security forces as well as the cold weather," said Abdel Rahman.
Internet-based activists had urged protests under the banner of "Russia is killing our children."
But Moscow said Syria's opposition "bears full responsibility" for the ongoing violence, while accusing the West of pushing regime opponents into armed conflict.
Arab and Western governments have so far resisted mounting calls for military aid to the outgunned and outnumbered rebels in Syria.
The US ambassador to Syria, Robert Ford, posted declassified photographs on his Facebook site that Washington said shows an army attacking a civilian area of Homs.
State Department spokeswoman Victoria Nuland said the "declassified US national imagery" shows the destruction of Homs.
She said Ford, who left Damascus when the US embassy was closed for security reasons on Monday, would continue to use Facebook to "talk to the Syrian people on a regular basis, along with his Twitter feed."
EU foreign policy chief Catherine Ashton said the world had to stand united in demanding a halt to the violence and for Assad to step down, saying she was appalled by reports of "the brutal attacks by the Syrian armed forces in Homs."
Saudi King Abdullah said world confidence in the United Nations had been "shaken" after Russia and China vetoed a resolution condemning the Assad regime's crackdown.
In Geneva, the UN rights office said Syrian officials responsible for carrying out or ordering crimes against humanity should face prosecution by the International Criminal Court.
The opposition Syrian National Council, meanwhile, said it expects to be recognised by several Arab states within days. So far only post-revolt Libya has recognised the umbrella group as its sole Syrian interlocutor.
Turkey also said it was open to a US proposal for a "Friends of Democratic Syria" group, an initiative that seemed to be gaining momentum on Friday.
A Western diplomat in London said that the 22-member Arab League was likely to launch such a grouping and appoint a special envoy to Syria at a meeting this weekend.
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The military, headed by Mubarak's long-time defence minister Field Marshal Hussein Tantawi, has said it will deploy additional troops across the country in response to the calls for a day of disobedience.
On Friday, thousands of protesters snaked through Cairo's streets to bypass military cordons and reach the defence ministry, chanting "Down with military rule!"
In a statement read out on state television late on Friday, the Supreme Council of the Armed Forces (SCAF) said it would not bow to threats or plots against the state.
"We will never yield to threats, and we will never give in to pressure," the SCAF said.
"We tell you quite frankly that our dear Egypt faces plans aimed at striking at the heart of our revolution.
"We are facing plots against the nation aiming to undermine the institutions of the Egyptian state, and to topple the state itself so that chaos reigns."
The military, which has brutally quashed several protests in the past year, has played off the abundant suspicion in Egypt of foreign conspiracies.
Students in several universities have called for strikes for Saturday, with secular youth groups which spearheaded the revolt against Mubarak also taking part.
Tareq al-Khouly, an organiser of the April 6 youth group, said the plan was for a one-day strike which could be extended.
In a joint statement on Friday, the groups urged Egyptians "to support these strikes in order to end the unjust rule and build a nation in which justice, freedom and dignity prevail."
The call for strikes and protests has divided the country's political forces, with the Muslim Brotherhood -- the big winner in recent parliamentary elections -- coming out against it.
Many Egyptians complain that the economy has been battered by the lack of security and deadly violence in the wake of the 18-day revolt that forced Mubarak to resign on February 11 last year.
Protests against the military, idolised immediately after the revolt for not siding with Mubarak, have heightened fears among many that the Arab world's most populous nation could veer towards chaos, as the military itself warns.
On Friday the SCAF said the nation was at "the most dangerous turning point on our road to liberty, democracy and social justice."
Young activists who spearheaded the revolt against Mubarak believe the generals will try to exercise power through a pliant civilian government after presidential elections later this year.
The activists say the military should hand power to parliament, elected over three rounds in November and December, or to a civilian council ahead of presidential elections set to take place before the end of June.
The SCAF statement said it was determined to transfer power to an elected civilian body.
"We have kept the first promise and returned legislative power to the people's assembly," it said, adding that the parliamentary election took place in an atmosphere of "liberty and integrity."
"Presidential power will pass to the president of the republic after the election ending the period of transition, and your faithful army will revert to its original role," the military statement said.
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After Hollywood disaster fare such as Oliver Stone's "World Trade Center" and Paul Greengrass's "Flight 93", "Extremely Close" is less about the attacks themselves than the shock and sorrow left in their wake.
The film, which is based on the bestseller by Jonathan Safran Foer and has been nominated for an Academy Award as best picture, tells the story of Oskar, whose father is trapped in the World Trade Center that September morning.
When the boy finds a key left by his late father, played by Tom Hanks, he goes on a search of New York's five boroughs trying to find the matching lock.
The odyssey brings him closer to his widowed mother (Sandra Bullock) and a mysterious stranger, played by Max von Sydow, who has been nominated for a best supporting actor Oscar.
Daldry was asked whether the film's focus on America's ongoing grief did not lose sight of the suffering felt by families where the country has since waged war.
"This particular story is focused on one family and the consequences on one family but do I think there should be films about the consequences of what happened in Iraq or what continues to happen in Afghanistan? Yes, I do think that is true. I think it's important those stories are told," he said.
Daldry said the pain of September 11 remained raw in New York, where he has a home and where the film's images of Hanks' body hurtling from the North Tower have come in for sharp criticism.
"There's lots of issues around 9/11 that we were very aware of and I suppose that's also because of the reaction and the response to Jonathan's book," he said.
"We were very aware that there would be a certain amount of controversy about what we would and wouldn't show. We tried to keep a number of family groups very close to us in the preparation for the film.
"In the end you had to trust your instincts about what you think is appropriate."
Von Sydow, 82, said he brought his own vivid memories of 9/11 to the role.
"My wife and I were driving along the highway in the south (of Sweden) when my mobile phone rang and someone called from Paris and said 'Come home immediately, there's a war, there's a war. And drive, don't go by airplane'," said von Sydow, who lives in France.
"That is a moment I will never forget and most of us I guess will always remember that moment."
Thomas Horn, the 14-year-old who plays Oskar, said he had no personal recollection of 9/11 but talked to families of victims in New York to prepare for the part.
"I became more emotionally connected to the event definitely by going to New York and talking to the people who lost their relatives," he said.
"It was really sad to talk to them. But in some ways I was happy they seemed to have found ways to move on from their loss."
"Extremely Loud and Incredibly Close" screened out of competition at the Berlin film festival, which runs to February 19.
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