Sana'a, Yemen - Britain warned its subjects Thursday against non-essential travel to Yemen after three attacks in recent weeks targeted US and Western interests in Sana'a.

Britain's Foreign Office updated its travel advisory on its website to advise against non-essential travel to Yemen, citing a "high threat from terrorism."

"We advise against all non-essential travel to Yemen," the upgraded advisory said.

"There is a high threat from terrorism in general in Yemen including against Western and British interests," it said.

It asked Britons to "be particularly vigilant in public places frequented by expatriates and foreigner travelers."

"We believe that terrorists continue to plan attacks," the travel warning said.

The updated travel advice comes one day after a bomb exploded outside the offices a Canadian oil firm in Sana'a. No one was hurt in the blast, police officials said.

The bomb went off outside the headquarters of the largest oil company operating in Yemen, Canadian Nexen Petroleum. A second bomb was defused by police.

On April 6, a mortar attack in Sana'a targeted a high-security residential compound housing US diplomats and other Westerners working for foreign oil companies in Yemen. There were no casualties in the attack, which was later claimed by the terrorist network al- Qaeda.

The US embassy in Yemen on Tuesday asked non-essential staff and family members to leave Yemen.

On March 18, four mortar shells were fired at the US embassy compound in Sana'a but missed their apparent target and struck a girls' school adjacent to the embassy.

An embassy guard was killed in the attack, and three embassy guards and 13 female students were wounded. Official media said later that the terrorist network al-Qaeda was behind the attack. (dpa)