A North Korean vessel has been captured by pirates off Mogadishu port in Somalia, a maritime watchdog said Tuesday.

The Malaysia-based International Maritime Bureau's (IMB) Piracy Reporting Centre said the situation was still developing and that it was unable to release details of the vessel or its crew as yet.

"We received the report and now we are liaising with the North Korean embassy in London and also the North Korea Maritime Administration," IMB spokesman Noel Choong told AFP.

"We cannot divulge too much information because things are moving," he said.

Andrew Mwangura, head of the East African Seafarers' Assistance Programme, was quoted as telling Yonhap news agency in Seoul that the vessel was a South Korean cargo ship with 22 crew on board and that it was taken Monday or early Tuesday.

Choong said the vessel had been identified as North Korean. He declined to specify how many were on board but said that the figure of 22 was incorrect.

Security officials in Mogadishu identified the vessel as the MV Dia Honga Dan and said that a Somali clan militia charged with protecting it had seized the vessel and its crew.

"The ship was hijacked by security men who were on board and were supposed to be protecting it. The reason for the hijacking is unclear," said a port official who requested anonymity.

A spokesman for the African Union peacekeepers from Uganda, which guard Mogadishu port, confirmed the seizure of the ship that was anchored outside the port in southern Mogadishu.

"It was far away from the seaport, it was at the anchorage. The hijacking was masterminded by the same people who were supposed to bring it into the docking," Captain Paddy Ankunda told AFP.

Ankunda said the militiamen were asking for 15,000 dollars to free the freighter that arrived in Mogadishu 10 days ago and had already unloaded.

The incident was the second piracy attack off the lawless Somali coast in recent days.

On Sunday, a Japanese chemical tanker with 23 Korean, Filipino and Myanmar crew on board was hijacked off the coast of northern Somalia. The fate of the ship and its crew remains unknown.

Rampant piracy attacks off Somalia's vast and largely unpatrolled coastline stopped in the second half of 2006 during six months of strict rule by Islamists, who were ousted by Ethiopian and Somali government troops at the end of the year.

Somalia, which lies at the mouth of the Red Sea, has been without an effective government since the 1991 ouster of dictator Mohamed Siad Barre sparked a bloody power struggle.