MOGADISHU (AFP) - Gunmen on Sunday killed the head of the UN Development Programme in the Somali capital, a UN official said, the latest fatality in a string of attacks on aid workers in the lawless country.

Osman Ali Ahmed was shot at close-range as he left a mosque in southern Mogadishu's Bulohube district, and later died while undergoing treatment in a Africa hospital military hospital.

"The gunmen shot Ahmed as he was leaving evening prayers in the mosque in Bulohube. He was taken to hospital where he died because of his wounds," a UN official told AFP on condition of anonymity.

His wife Nasteho Abukar Yusuf confirmed Ahmed's death.

"They shot him several times in the head and chest. He was taken to African Union peacekeepers' hospital where he died," she told AFP.

Several witnesses said a second man, whose identity is yet to be established, was seriously wounded in the attack which appeared to be premeditated.

UN officials have repeatedly appealed to the Somali government and Islamist militants, who are fighting for the control of the country, to spare aid workers, many of whom have been killed or kidnapped in the recent months.

Aid groups have scaled down operations in Somalia owing to increased insecurity, largely blamed on Islamist militants who have waged a guerrilla war since they were ousted by joint Somali-Ethiopian forces in early 2007.

The African Union Mission to Somalia (AMISOM) has deployed 2,600 peacekeepers in Somalia -- well short of a promised 8,000 troops -- but so far it has failed to stem the violence and unrest.

At the AU summit in Egypt earlier in July, the AU extended the troops mandate by six months but pleaded with the UN to take over the under-manned, under-equipped force in order to pave the way for the withdrawal of Ethiopian troops who entered in Somalia late 2006 to bolster the feeble Somali government.

Neither the Somali government nor the AU peacekeepers are capable of protecting aid workers, officials say. The troops from Uganda and Sudan have only managed to secure Mogadishu's seaport and port area, leaving the rest of city to the warring camps.

At least 2.6 million Somalis are facing hunger due to acute food shortages spurred by a prolonged drought, insecurity and high inflation. The UN's famine monitors have warned that the figure could hit 3.5 million by the year's end.

Aid workers have been constantly targeted since the 1991 ousting of dictator Mohamed Siad Barre paved the way for a breakdown in the state machinery and a rise in factional warfare.

A bloody power-struggle has defied numerous UN-backed bids to restore stability in this lawless nation which is home to up to 10 million people and where western intelligence warn that Al-Qaeda linked element planed to make an haven.

On June 9, the Somali rival sides signed a truce agreement at UN-mediated talks in Djibouti.

The deal gave both sides one month to implement a cessation of hostilities but it was opposed by Islamist hardliners who have continued their struggle, insisting that an Ethiopian withdrawal was a precondition to talks.

Mediators are currently struggling to bring the Islamist elements into the truce with analysts warning that their absence would render the armistice useless.

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