Nairobi - Somali pirates have released a Togo-flagged ship originally routed to carry food aid to the Horn of Africa nation, the World Food Programme (WFP) said Monday.

A Nairobi-based WFP spokesman, citing the MV Sea Horse's owners, said that the ship, which was taken on April 14, was released on Friday.

There was no official information on whether a ransom was paid, although some reports suggested that as much as 100,000 dollars may have changed hands.

The 5,000 ton Lebanese-owned vessel was seized as it travelled to Mumbai to load over 7,000 metric tons of food aid for Somalia, where a combination of drought, conflict and rising food prices has left millions facing hunger.

Pirate activity has picked up in recent weeks after a lull due to bad weather. Almost 30 ships have been attacked in the last four weeks.

Fifteen ships, with around 250 crew members, are still being held hostage.

On Sunday, a Canadian warship warded off a pirate attack on a Norwegian tanker in the Gulf of Aden.

The destroyer Winnipeg and US Navy vessels chased and caught the pirates. However, they were forced to release them as Canadian law did not allow their prosecution.

On Saturday, legal reasons also forced Dutch troops to release nine pirates they captured after freeing 16 Yemeni fishermen and their vessel, which was being used to attack a tanker.

The highest-profile attack in recent weeks was the failed hijacking of the US-flagged Maersk Alabama.

The Alabama's crew repelled the hijacking but the captain was held hostage for five days on a lifeboat. He was freed Sunday when US Navy snipers killed the three pirates holding him.

In 2008, pirates seized more than 40 vessels in and around the Gulf of Aden and collected tens of millions of dollars in ransoms, prompting the international community to send warships to the region.

The presence of the warships, which patrol an area of about 2.85 million square kilometres has had little effect. Observers say that only by tackling insecurity and poverty in Somalia will piracy finally be halted.

Somalia has been without a functioning government since the 1991 ouster of dictator Mohamed Siad Barre.

US Secretary of State Hillary Rodham Clinton on Wednesday announced a four-point plan to counter piracy, including steps to improve security, policing and governance in Somalia. (dpa)