Yemeni troops backed by armoured vehicles took control of the southern town of Jaar on Tuesday after Al-Qaeda gunmen who overran it a year ago withdrew during the night, witnesses said.

The taking of the town marks the first major victory of an all-out military offensive launched a month ago against the jihadists, who have controlled most of the southern province of Abyan for more than year.

Armoured vehicles moved into the centre of Jaar hours after Al-Qaeda militants withdrew towards the nearby town of Shuqra, when "fighting with the army became fiercer," one resident told AFP.

Locals said they saw vehicles carrying militants, weapons and furniture heading east towards Shuqra, where many of the Al-Qaeda leadership are believed to be holed up.

The militants distributed pamphlets in the town apologising to residents for dragging Jaar into a conflict with the army and for the damage caused by the fighting, according to locals.

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

Since the offensive began, 485 people have been killed, according to an AFP tally combined from different sources. This includes 368 Al-Qaeda militants, 72 soldiers, 26 local armed men and 19 civilians.