ADEN - Militants attacked a police station in Yemen's southern city of Jaar late on Tuesday night, killing two policemen and injuring three others, a security official told Reuters on Wednesday.

"Two militants riding motor bikes opened fire on a police station in Jaar at around midnight on Tuesday," the official, speaking on condition of anonymity, said.

He added that the militants are believed to be members of Ansar al-Sharia, a group which swears allegiance to al Qaeda in the Arabian Peninsula.

"The two men managed to escape on their motorbikes and there's a search for them."

Ansar al-Sharia seized control of several cities in Abyan province last year during a wave of protests that forced former President Ali Abdullah Saleh to step down.

Yemen's army drove militants from the strategic city of Jaar and the provincial capital of Zinjibar in June, and Tuesday's incident would be Ansar al-Sharia's first shooting attack in Jaar since then, the official said.

The military's offensive was seen as a breakthrough in a U.S.-backed offensive aimed at securing stability in the region. However, some resident eyewitnesses in Jaar have said armed members of Ansar al-Sharia still roam freely in the city.