"Four of our men were killed when a suicide bomber detonated a car full of explosives at a checkpoint between Loder and Shaqra" in Abyan, the source said on condition of anonymity.

The militiamen from the Popular Resistance Committees are mainly armed local residents fighting alongside the Yemeni army against Al-Qaeda-linked militants.

A member of the committees told AFP that militiamen foiled a similar attempt by another suicide attacker who passed by a checkpoint held by the gunmen.

The bomber blew himself up after militiamen pointed their guns at him to shoot him. He was killed alone, according to the same source.

Yemeni forces launched an all-out offensive on May 12 aimed at reclaiming Abyan's capital Zinjibar and other towns and cities in the province lost to Al-Qaeda over the past year.

Since the assault began, at least 391 people have been killed, according to an AFP tally compiled from official statements, including 285 Al-Qaeda fighters, 66 military personnel, 22 local militiamen and 18 civilians.