NAIROBI, April 9 (Reuters) - Attacks by pirates off Somalia are making it ever harder for the U.N. food agency to deliver relief aid to the hungry in east Africa and the Horn of Africa, the World Food Program (WFP) said on Thursday.

Piracy off Somalia escalated once again with the capture of five vessels since the weekend, and the brief hijack of a ship with 20 American crew. Its captain is still being held hostage on a lifeboat. [ID:nNN0810184]

The attacks are going increasingly further south and east of Somalia's coastline far into Indian Ocean waters.

Attacks on ships to-and-from Kenya's Mombasa port, which is a hub for aid and commercial deliveries, could raise insurance costs and mak...

NAIROBI, April 9 (Reuters) - Attacks by pirates off Somalia are making it ever harder for the U.N. food agency to deliver relief aid to the hungry in east Africa and the Horn of Africa, the World Food Program (WFP) said on Thursday.

Piracy off Somalia escalated once again with the capture of five vessels since the weekend, and the brief hijack of a ship with 20 American crew. Its captain is still being held hostage on a lifeboat. [ID:nNN0810184]

The attacks are going increasingly further south and east of Somalia's coastline far into Indian Ocean waters.

Attacks on ships to-and-from Kenya's Mombasa port, which is a hub for aid and commercial deliveries, could raise insurance costs and make shippers wary of going there, said Peter Smerdon, WFP's senior public affairs officer for the region.

There are 232 WFP containers among 400 holding relief aid on the U.S.-flagged ship temporarily seized by pirates this week.

The aid was destined for Somalia, Kenya and Uganda.

"If we have piracy off Somalia making it difficult to deliver food, we will have to cut rations and people will miss distributions and people will go hungry," Smerdon told Reuters.

"You get increased insurance rates because (the ships) are being hijacked and it also makes shippers more reluctant to come to this region."

Piracy has been rampant in waters around the Horn of Africa. There were 111 attacks last year off Somalia and the Gulf of Aden, more than double the 2007 figure.

The cases accounted for roughly a third of all piracy in the world.

Often armed with heavy weapons, such as rocket launchers and automatic rifles, the pirates attack large cargo ships and tankers to demand ransoms for the release of their crew.

Mombasa, south of Somalia, is a vital hub for receiving food assistance for Sudan, Uganda, Rwanda, Somalia and Kenya.

"The food situation in east and Horn of Africa is extremely serious. In Somalia we need to feed 3.4 million people -- which is like half the population -- because t