Sana'a, Yemen  - The US embassy in Yemen on Tuesday asked its non-essential staff and family members to leave Yemen after a mortar attack on a residential compound housing Americans in Sana'a.

In a "warden message" posted on its website, the embassy said the US Department of State had ordered the departure of non-emergency diplomatic staff from Yemen.

"The Department of State has ordered the departure of non- emergency embassy staff and family members from Yemen," the note said.

It said the ordered departure was prompted by the attack on the embassy on March 18 and the April 6 attack on a Sana'a residential compound.

There were no casualties when the compound was hit by three mortar shells late Sunday, police said. They said the attackers managed to escape.

"Embassy employees are not authorized to travel outside of Sana'a and have been advised to avoid hotels, restaurants, and tourist areas," the embassy's note said.

The embassy advised its employees to "strictly limit their exposure in public places until further notice."

It also called on US citizens in Yemen to "exercise caution and take prudent security measures, including maintaining a high level of vigilance."

On Monday, a government official said an al-Qaeda wing in Yemen has claimed responsibility for the attack against the residential compound.

The high-security residential complex in the Haddah neighbourhood houses US diplomats and other Westerners working for foreign oil companies in Yemen.

Police said the attack only shattered windows of one villa inside the complex.

A police officer at the scene told Deutsche Presse-Agentur dpa that attack was similar to the last month's attack against the US embassy, when four mortar shells were fired at the embassy compound, but missed their target and struck a girls' school adjacent to the embassy.

An embassy guard was killed in the March 18 attack, while three embassy guards and 13 female students were wounded. Official media said later the terrorist network al-Qaeda was behind the embassy attack. (dpa)