Nairobi - Pirates have seized a Ukrainian cargo ship carrying tanks off the coast of Somalia, a maritime official confirmed Friday.

"The ship was grabbed yesterday evening as it sailed to (the Kenyan port of) Mombasa," Andrew Mwangura of the East African Seafarers' Assistance Programme told Deutsche Presse-Agentur dpa. "It was carrying military equipment, including tanks."

The Russian Interfax news agency late Thursday reported that the Belize-flagged vessel was carrying a shipment of 30 T-72 tanks, armoured personnel carriers and munitions. The shipment was bound for South Sudan.

Twenty-one crew members were on board - 17 Ukrainians, three Russians and a Latvian - when the ship was chased down and boarded by armed men in three launches.

Somali authorities were unable to give any information on the current whereabouts of the ship.

Piracy is rife off the lawless Somali coast, with armed groups now holding over a dozen ships and around 200 crew members.

The pirates often demand ransoms in excess of 1 million dollars for the return of the vessels and their crews.

Observers have expressed concern that some of the pirates have links to the ongoing bloody insurgency in the Horn of Africa nation and are helping fund it through piracy.

Somalia's transitional federal government, which has no navy to speak of and is embroiled in combating the insurgency, has been unable to control the pirates

The United Nations Security Council in June approved incursions into Somali waters to combat the pirates and the US Naval Central Command recently set up a security patrol in the area.

However, the measures appear to have had little effect so far. (dpa)