ADEN (Reuters) - A drone strike killed four suspected al Qaeda militants in a car in the southern Yemeni province of Shabwa on Friday, local officials and residents said.

The car burst into flames and plumes of black smoke were billowing above the main road where the drone struck, they said.

Al Qaeda propaganda brochures were scattered over the ground by the road, local officials said.

During nine months of civil war and military intervention by a Saudi-led Gulf Arab coalition last March, the United States has kept up drone strikes against jihadist groups in Yemen.

With near-daily air strikes, Gulf Arabs and the U.S. are trying to rout the Iran-backed Houthis and forces loyal to former president Ali Abdullah Saleh, who now control areas close to the presidential palace, and restore the internationally recognized government of President Abd-Rabbu Mansour Hadi.

Hadi fled south to Aden, a strategic port and shipping hub, early last year after the Houthis, a clan from northern Yemen, seized the capital Sanaa and forced him out.

In the chaos around the Houthis push south, Al Qaeda in the Arabian Peninsula (AQAP), an affiliate of the global Sunni Muslim militant organization, has expanded its foothold in a country which has a long and porous border with Saudi Arabia.

The Sunni-ruled kingdom sees the Shi’ite Houthis as a proxy for Iran, its main regional adversary.

Viewed by Western analysts as the most dangerous arm of al Qaeda, AQAP claimed responsibility for the Jan. 25 attack in Paris on the satirical French magazine Charlie Hebdo.

AQAP has suffered setbacks in recent months, losing its leader and several senior leaders in U.S. drone strikes, and is facing competition from the new Yemen branch of Islamic State.