Dozens of al Qaeda militants took control of the southern Yemeni town of Ahwar on Saturday, residents said, consolidating the group's control over much of the region.

The coastal city and surrounding district, in Abyan province, is home to more than 30,000 people and is an important geographic link between the major port city of Mukalla to the east and the smaller town of Zinjibar, both of which Al Qaeda seized months ago.

"At dawn this morning the al Qaeda gunmen clashed with the Popular Resistance forces, killing three of them," one resident said. "They attacked the sheikh in charge of the area and after he escaped set up street checkpoints and planted their black flag on government buildings."

Separately, two gunmen riding a motorbike killed one of the most senior commanders in the Popular Resistance, a loose confederation of southern militias opposed to al Qaeda.

Sheikh Mazen al-Aqrabi was killed along with a bodyguard in Yemen's second-largest city of Aden in the southwest, an eyewitness and a security official said. The gunmen were believed to be from al Qaeda, according to the official.

Residents in Aden's Mansoura neighbourhood also reported heavy explosions on Friday night as gunmen launched shoulder-fired rockets in a failed attempt to take over a container port.

Al Qaeda in the Arabian Peninsula (AQAP), a Sunni Muslim group that claims to be subordinate to the main global militant organisation, has expanded during Yemen's civil war.

Viewed by Western analysts as the most dangerous arm of al Qaeda, it claimed responsibility for the deadly January 2015 attack in Paris on the satirical French magazine Charlie Hebdo.

AQAP's advance in Yemen triggered a military intervention by a Gulf Arab coalition in March last year. The Saudi-led forces, which back the ousted government of President Abd-Rabbu Mansour Hadi, have clashed with the ascendant Houthi movement which they fear is a proxy for Shi'ite Muslim Iran. The Houthis and Iran deny this.

Hadi's Aden-based government has struggled to reverse AQAP's advance which has reached areas close to the presidential palace.

Even so, AQAP has suffered setbacks, losing its leader and several top officials in U.S. drone strikes, and is facing competition from the new Yemen branch of jihadist group Islamic State.-Reuters