These committees are made up of people who have taken up arms to defend their villages or neighbourhoods against the rebels.
The fighting in Homs was concentrated in the Crac des Chevaliers region, home to a historic Crusader castle, and Wadi al-Nassara, a valley where a number of Christian villages are located.
The Britain-based Observatory which gave Thursday's toll, also reported fierce battles and army shelling in Qadam in southern Damascus where anti-regime sentiment is strong, as well as shelling in nearby Assali.
Clashes also broke out elsewhere in the city, including in the Sayyida Zeinab area of the southeastern outskirts, home to an important Shiite Muslim shrine, the group said.
In the central province of Hama, Kafr Zeita, another main arena of the nearly 18-month revolt against President Bashar al-Assad, came under fierce shelling by regime forces for a second consecutive day, according to activists.
Elsewhere, a military source said the army has retaken the strategic Barkum bridge south of Aleppo on the highway to Damascus, three weeks after rebels seized it.
In the west of Aleppo city itself, regime forces have advanced towards the Rashid mosque in the Izaa district amid fierce fighting, a military source said.
And more than a dozen people were killed when a mortar round exploded for the first time in a Kurdish quarter of the city, the Observatory and witnesses said.
-- Alleged new 'massacre' --
In an alleged new massacre, 23 corpses, including those of women and children, were found in Zamalka, in Damascus province, said the Observatory, as anti-Assad activists pointed the finger at the regime.
The town has been a hotbed of anti-regime protest, army raids and clashes between regime forces and rebels.
The Observatory also reported that two kidnapped brothers of a Syrian rebel commander were killed on Thursday.
The men were seized at an army checkpoint on Wednesday night, it said. They were found dead in the Qadam district of Damascus amid a sharp increase in reports of abductions across the country.
Amateur video posted on YouTube by activists showed the bodies of the two men, identified as Mohammed and Ahmed al-Zakh, covered in blood. The head of one of the victims had been partly blown off.
A toll compiled by the Observatory said at least 90 people, including at least 33 civilians, were killed in violence across Syria on Thursday, a day after 176 people died, most of them civilians.
The violence has claimed more than 26,000 lives since it erupted in mid-March 2011, according to the Observatory.
Meanwhile, Putin lambasted the West and Arab countries for their position on Syria.
"Why should Russia be the only one reassessing its position? Perhaps our negotiating partners should reassess their position," he told Russia Today television.
"To us, the most important thing is to end the violence, to force all the sides in the conflict... to sit down at the negotiating table, determine the future and ensure the security of all the participants of the domestic political process," he said.
"Only then move on to these practical steps about the internal organisation of the country itself."
Putin has previously rejected providing asylum to Assad and insisted that Moscow still viewed either him or his representatives as an integral part of the negotiating process.
Moscow has stirred Western and Arab world anger by vetoing three UN Security Council resolutions that would have slapped sanctions on Assad during the conflict.
The Russian foreign ministry, meanwhile, said it had full assurance that the chemical weapons stockpile amassed by the regime was safe and would not be used against Assad's foes.
"We are fully confident -- and have the official assurance from Damascus -- that this country's government is taking all the necessary measures to guarantee the chemical arsenal's safety," said Deputy Foreign Minister Sergei Ryabkov.
Meanwhile, France and Britain have agreed on the need to speed up the transition from Assad's regime to a new government, French President Francois Hollande said.
"David Cameron and I are in total agreement. We must accelerate the political transition (and) help the opposition to form a government," said Hollande, after talks with the British prime minister in London.
"We have a duty to help the Syrian opposition in any way we can," Hollande added in a statement with Cameron at his side.
Britain and France are among the Western nations leading calls for Assad to step down in a bid to end the bloody conflict, which erupted in March 2011.
In that vein, the Syrian foreign ministry denounced as a "flagrant interference in the domestic affairs of the country," a call on Wednesday by Egyptian President Mohamed Morsi for Assad to go.