"The failed terrorist attack that targeted the British ambassador in Sanaa carries the fingerprints of Al-Qaeda," said the interior ministry website, citing security authorities.
The interior ministry later named the assailant as Othman Ali Nouman al-Salawi, 22, from Taiz south of Sanaa, according to the defence ministry news website 26sep.net.
"This operation reflects the state of despair which has hit the terrorists after the painful pre-emptive strikes which they received in their hideouts at the hands of security services," the website said.
It was referring to a spate of deadly air raids and ground assaults targeting suspected Al-Qaeda hideouts in the Arab world's poorest country and carried out with Western backing since the jihadist network's Yemeni branch claimed the attempted bombing of a US airliner on December 25.
The suicide bomber threw himself at the convoy of the diplomat "wearing an explosive belt," the interior ministry said.
Three bystanders, one woman and two men, were lightly wounded in the blast, and witnesses said the attacker's body was torn to pieces.
British Foreign Secretary David Miliband condemned the bombing, saying it only strengthened London's resolve to tackle international terrorism.
"I condemn the attack this morning in Sanaa against the British ambassador to Yemen," Miliband said.
"Thankfully Tim and all his staff are unhurt. I am grateful for their professionalism and for the role of the Yemeni security authorities who acted quickly and calmly to deal with the situation.
"Today's incident only strengthens our resolve to work closely with the government of Yemen to tackle international terrorism."
London hosted an international conference in January on the Islamic militant threat against Yemen, Al-Qaeda leader's Osama bin Laden's ancestral homeland. It was also a prime mover behind a follow-up aid meeting in the Saudi capital Riyadh the following month.
The British Foreign Office said the embassy in Sanaa would remain closed to the public "for the time being".
"We advise all British nationals in Yemen to keep a low profile and remain vigilant," it added.
A notice on the British embassy website added that the timing of its reopening would be "reviewed after the Yemeni weekend," which runs from Thursday to Friday.
Torlot has been the ambassador to Yemen since 2007.
Witnesses said the bomber was slow in targeting the diplomat's vehicle and that the only damage was to a police car escorting the convoy.
"The suicide bomber, dressed in sports gear, strapped his body with explosives and attempted to target the British envoy but fortunately failed," said Mohammed al-Basha, spokesman for Yemen's embassy in the United States.
American and British missions were shut for some days in January following indications that the Yemen branch of Al-Qaeda was targeting Western interests.
Yemen's defence ministry said in late December that an attack against the British embassy was foiled after an Al-Qaeda cell in Arhab, 35 kilometres (20 miles) north of the capital was dismantled.
The attack on the British embassy "was to be modelled on the operation that was carried out against the American embassy" in 2008, which killed 16 people, the defence ministry said at the time.
Monday's bombing was the first suicide attack in Yemen since March 2009 when a South Korean delegation was attacked while investigating an earlier bombing which killed four South Korean tourists.
No one was killed or wounded in the second blast.