Air strikes in south Yemen killed at least seven militants, a security official said on Thursday, while armed tribesmen entered the city of Zinjibar to try and wrest it from militant control.

The official said there were likely more casualties in the two air strikes north of Zinjibar, capital of Abyan province, but that militants had dragged bodies away from the area. At least 35 people were wounded, he said.

Violence has gripped Yemen since February when protests erupted calling for an end to President Ali Abdullah Saleh's 33-year rule.

A security official said the air strikes were carried out by the Yemeni air force, refuting reports by residents that the planes looked like American drones.

Residents said the strikes hit a government building, where security officials said 50 militants were suspected of hiding.

"The airplanes were small in size and hovered in the city's skies at midnight," Mohammed Maseeny, a resident, said.

Later on Thursday, militants raided an Abyan hospital, stealing medicine and kidnapping a medic.

Previous efforts by the Yemeni army to flush militants out of Abyan had not been successful, but tribesmen said they were getting the upper hand against militants and that some had retreated due to increasing hostility from residents, the military and the tribes.

Tribesmen said they had entered Zinjibar but that militants appeared to have withdrawn from the city where streets were deserted and power was cut. Fearing an ambush by militants, the tribesmen said they withdrew to the outskirts of the city.

Others said they saw militants in the distance heading towards the Hutat Mountains, a militant stronghold which has served as a refuge for nearly a decade.

Reuters