At least 11 al Qaeda militants, including a number of local leaders, were killed in an overnight air strike in southern Yemen, local residents said on Tuesday.

They said an unidentified drone attacked the militants while they were travelling in two vehicles east of the city of Lawdar in Abyan province in southern Yemen.

A tribal leader said at least four of those killed were local al Qaeda leaders. Residents said no civilians were hurt in the air strike.

The United States has used drones repeatedly to attack al Qaeda militants in Yemen. Last September, a U.S. drone killed U.S.-born cleric Anwar al-Awlaki, described by U.S. officials as chief of external operations for al Qaeda in Yemen.

The latest attack could deal a blow to al Qaeda which has exploited unrest and protests against President Ali Abdullah Saleh to strengthen its hold on remote areas in southern Yemen in recent months.

An opposition-led government has been set up in Yemen after Saleh agreed in November to transfer authority to his deputy ahead of presidential elections in February.

But protests have continued and activists are pressing on with demands that Saleh be tried for alleged killings of demonstrators and that the government is purged of members of his family.

(Reporting By Mohammed Mokhashaf, writing by Mirna Sleiman Editing by Maria Golovnina)