The UN's World Food Programme says an attack on a ship delivering food aid to Somalia has renewed worries about piracy in the area.

Supplies to some one million people are said to be threatened.

The WFP-chartered vessel was attacked on Saturday off the Somali port of Merka after it had just delivered 4,000 tons of food.

The head of the WFP said other ships were now refusing to sail to Somalia.

In a statement the WFP executive director, Josette Sheeran, said: "We urge key nations to do their utmost to address the plague of piracy, which is now threatening our ability to feed one million Somalis."

"This attack underscores the growing problem of piracy off Somalia which, if unresolved, will sever the main artery of food assistance to the country and to the people who rely on it for their survival," she added.

'Alarmed'

The pirates killed a guard who was among a group sent to intercept them after they attempted to hijack the vessel.

"WFP is very saddened and alarmed by the death of the guard, who showed great courage while the ship came under attack. We send our condolences to his family," Sheeran said.

The ship was on its way to the port of Dar es Salaam in Tanzania after delivering food aid to Merka, south of Mogadishu.

Last year the WFP had to suspend aid deliveries for weeks after the hijacking of two ships it had contracted.

Piracy has been rife off Somalia since the country slid into lawlessness in the 1990's although during the brief six-month rule of the Union of Islamic Courts last year, attacks decreased.

Many pirates claim to be coastguards, protecting waters against illegal fishing and the dumping of toxic waste.

BBC