Four killed, 10 wounded in Yemen Islamist clashes

They said fighters from Ansar al-Sharia launched a dawn attack on an army outpost near the city, which is in Abyan province where the group already controls significant territory, and about 120 km (75 miles) from the southern port city of Aden.

The group took that territory during the turmoil that led to the replacement of President Ali Abdullah Saleh by his deputy, a deal that Saudi Arabia and Washington hope will keep al Qaeda from getting a foothold near key oil shipping routes.

Mohammed Nasser, a resident of Lawdar, speaking by telephone with the sound of artillery and small arms fire audible, said the fighting lasted three hours.

"It is not the first attempt (by the group) to take control, but it's the biggest attack yet," he said. A local official said tribal militiamen joined the fighting alongside the military, and that at least 10 soldiers and tribesmen were wounded.

The Islamist conflict is only one of the challenges facing the new president, Abd-Rabbu Mansour Hadi, who took office vowing to fight al Qaeda, only to have more than 100 soldiers killed in a series of attacks in his first days in power.

Washington, which has pursued a campaign of assassination by drone and missile against alleged al Qaeda targets in Yemen, wants him to reunify a military that split between Saleh's foes and allies, and focus it on "counter-terrorism.

Yemen's main airport in the capital, Sanaa, was paralysed for a day after Hadi sacked the air force commander, a relative of Saleh, on Friday, and pro-Saleh officers responded by blockading the airport with vehicles.

A government official said they backed down only after warnings from the United States and the Gulf countries which crafted the deal that made Hadi president.

(Reporting by Mohammed Mukhashaf; Writing by Joseph Logan; editing by Tim Pearce)