NOUAKCHOTT - Suspected al Qaeda militants ambushed a Mauritanian army patrol on Monday in the desert north of the West Saharan Islamic state, and 12 soldiers were missing, feared either killed or captured, officials said.

The attack in rugged terrain near Tourine, about 100 km (60 miles) southeast of the iron ore mining town of Zouerate, was the worst to target the army since a military coup last month which deposed the country's elected civilian president.

Following the August 6 coup that toppled President Sidi Mohamed Ould Cheikh Abdallahi, al Qaeda's North Africa wing called for a holy war in the country, which has been seen in the West as an ally in the U.S.-led global war against terrorism.

Al Qaeda has claimed an attack in December against the Mauritanian army in which four soldiers were killed. In 2005, gunmen from the same group, then calling itself the Salafist Group for Preaching and Combat (GSPC), killed 15 Mauritanian soldiers in a raid on a northeast garrison.

Zouerate's deputy mayor, Souleimane Barro, said "suspected Salafists" carried out the latest attack on the army patrol.

"Yesterday evening, five military vehicles left Zouerate, but they were caught in an ambush and came under heavy fire," Barro said, adding that only three of the vehicles in the five-vehicle convoy had returned to their base.

Military sources said the two vehicles left behind had caught the worst of the ambush fire.

They were carrying 12 soldiers, including the patrol leader, a captain, who were now feared to be either killed or captured, the sources, who asked not to be named, said.

At least one wounded soldier was taken to hospital in Zouerate, the region where Mauritania's main iron ore mining operations are located.

COUNTER-TERRORISM COOPERATION

The ambush was certain to add to fears that al Qaeda's North Africa branch, which has carried out bloody bombings in the Maghreb, is extending it operations further southwards into sub-Saharan Africa, which is a source of crude oil to the West.

Western donors like the United States and Europe, which have condemned the August 6 coup against Abdallahi, had been supporting the civilian Mauritanian president in his efforts to tackle what appeared to be a growing threat of Islamist militant violence.

In December, besides the attack against the army, militant gunmen also killed four French tourists and the incidents forced the cancellation of the annual trans-Saharan Dakar rally.

An al Qaeda attack on the Israeli embassy in February highlighted Mauritania's status as one of the few Arab countries with diplomatic ties to the Jewish state.

The August 6 coup leader, Mohamed Ould Abdel Aziz, vowed after his military takeover that he would crack down on militants.

But the United States and France have already suspended some non-humanitarian aid to Mauritania after the coup and have threatened to impose sanctions against members of the ruling junta unless it releases Abdallahi, who is being detained.

In its August 12 call for a "holy war" in Mauritania, the al Qaeda Organisation in the Islamic Maghreb said the generals who toppled Abdallahi in the coup were probably acting with a green light from "infidel states; America, France and Israel".