Somali pirates have released a Lebanese-owned cargo ship seized last week as it headed to pick up food aid for Africa, a UN spokesman said today.

The Togo-flagged MV Sea Horse was released on Friday, UN World Food Program spokesman Peter Smerdon said, citing the ship's operators. He had no more details and it was not known if a ransom was paid.

The release was rare good news in the pirate crisis plaguing the Horn of Africa. Pirates still hold at least 17 other ships and around 300 crew. Most ships are held for multi-million-dollar ransoms.

Somali clan elder Abdisalan Khalif Ahmed told The Associated Press from the Somali pirate haven of Harardhere that gunmen released the ship after they found out it was supposed to pick up food destined for Somalia.

Some pirates have agreed not to target ships carrying relief supplies, but pirate gangs are controlled by rival clans and do not operate in concert. Other freighters carrying food aid have also been attacked recently, including the US-flagged Maersk Alabama, whose American Capt. Richard Phillips was held hostage for five days on a drifting lifeboat until he was freed on 12 April by US Navy snipers.

The MV Sea Horse was hijacked on 14 April off the Somali coast after it was surrounded by several pirate skiffs. The freighter was heading to Mumbai, India, to pick up 7,327 tons of WFP food destined for Somalia, but was not yet under WFP contract.

WFP is feeding 3.5 million Somalis this year, or about half of the country's inhabitants. That requires shipping 43,000 tons of food every month, some 90 per cent of which is sent by sea. Flying in food aid is too expensive, and roads in the lawless country are plagued by bandits.

Pirate attacks have increased in recent weeks, with gunmen from Somalia searching for targets further out to sea as ships try to avoid the anarchic nation. Pirates have attacked more than 80 boats this year alone, nearly four times the number assaulted in 2003, according to the Kuala Lumpur-based International Maritime Bureau.

Yesterday, repeated warning shots from Nato helicopters and warships ended a dramatic pursuit of seven pirates who tried to hijack the Norwegian-flagged tanker MV Front Ardenn in the Gulf of Aden, the Nato alliance said.

No shots were fired at the tanker, which escaped by taking evasive maneuvers. American and Canadian warships and choppers then chased the pirates' skiff in a seven-hour pursuit which began late Saturday and ended yesterday morning, said Cmdr. Chris Davies, from Nato's maritime headquarters in England.