The British ambassador narrowly escaped what appeared to be a suicide attack on his armored car while traveling to work Monday morning, Yemeni officials said.

British Embassy spokeswoman Chantel Mortimer said the ambassador, Timothy Torlot, was unhurt, but the attack underlined the precarious security in Yemen. An impoverished Arab nation in the southern corner of the Arabian Peninsula, Yemen has in recent years become a haven for al-Qaida militants taking advantage of the government's limited authority outside major cities and the control of rural areas by heavily armed tribes.

The Yemeni officials said the vehicle was passing through a poor neighborhood in the eastern part of San'a when an explosion went off nearby. They said they believed the attacker was wearing an explosives belt and that he was killed in the explosion.

There was no claim of responsibility for the attack, but it bore the hallmarks of al-Qaida.

Witnesses said the attacker was a young man who wore a school uniform, apparently as a disguise. The officials said the Noqm neighborhood where the attack took place was popular with militants.

The officials spoke on condition of anonymity because they were not authorized to speak to the media.

The Foreign Office in London said the embassy has been closed to the public and warned all British nationals in Yemen to "keep a low profile and remain vigilant."

"We can confirm that there was an incident in San'a this morning. There was a small explosion beside the British Ambassador's car. He was unhurt. No other embassy staff or British nationals were injured," the Foreign Office said in a statement.

"We are working urgently with the Yemen authorities to investigate what happened," it added.

Security was visibly tightened around the U.S. and British embassies following the attack. The area of the explosion was sealed off as Yemeni and British officials inspected the scene of the attack.

Yemen has been embroiled in a war against the al-Qaida militants, who have threatened to target foreign interests and diplomatic missions. Earlier this year, a number of Western embassies, including the U.S. and British embassies, shut down for days in response to threats of attack by an al-Qaida offshoot in Yemen.

Meanwhile, the government has received increased foreign counter-terror aid, aiming to fight the group.

Yemeni troops have been deployed in remote areas where al-Qaida is known to have set up strongholds, and they carried out a series of U.S.-backed raids against militant hideouts at the beginning of the year.

Al-Qaida in the Arabian Peninsula, an offshoot of Osama bin Laden's terror network, was formed more than a year ago when Yemen and Saudi militant groups merged.

But the fight against al-Qaida in Yemen has gained urgency since the failed Christmas Day attempt to bomb an American plane bound for Detroit. The suspect in that plot has said he received training in Yemen.

Al-Qaida militants are not the only security threat that President Ali Abdullah Saleh's government must deal with.

Yemenis in the south of the fragmented nation complain of neglect and discrimination by the north. The two halves of the country were separate nations until they united in 1990.

There also is a conflict in the country's north between government troops and Shiite rebels that the San'a government says are backed by Iran.

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Associated Press writers Jennifer Quinn in London and Sarah El Deeb in Cairo contributed to this report.