ADEN, Yemen: At least five people were killed in Yemen when a pro-government militia attacked Al-Qaeda-linked Islamist militants on Thursday, residents and militia sources said.

U.S.-allied Yemen has been grappling with an Islamist insurgency since popular protests forced President Ali Abdulah Saleh to step down in November 2011.

The United States considers Yemen an important ally against Al-Qaeda which it fears could use the country to plot attacks against its interests, and has regularly used drones to hit suspected militants there.

The sources said several people were wounded on Thursday in the fighting which broke out in the village of al-Qafr in the southern province of Abyan.

The two groups have regularly attacked each other since the pro-government Popular Committees were set up as a volunteer force against militants who exploited the 2011 political turmoil to seize territory and impose Islamic Sharia.

A U.S.-backed offensive by the Yemeni military last May recaptured ground from the militants and drove them out of towns they had seized the year before.

In the latest incident, dozens of pro-government Popular Committee members attacked Ansar al-Sharia fighters to avenge the killing of one of their colleagues the day before, militia sources said.

Three of those killed were members of Ansar al-Sahria and the other two were militia fighters, the sources said.

Yemen, situated next to the world's top oil exporter Saudi Arabia, is also fighting a separatist movement in the south and faces a potential challenge from Shiite Muslim rebels, known as Houthis, in the north.