Updated

A hijacked Malaysian-flagged ship that pirates have held off the coast of Somalia since November 2010 sank in rough seas, the European Union Naval Force said Monday, and a pirate commander said the ship had faced mechanical problems.

The European Union Naval Force said in a statement that the whereabouts of 15 crew members aboard the MV Albedo had not been confirmed. However, Hassan Abdi — a pirate commander in Hobyo, a pirate stronghold along central Somalia's Indian Ocean coastline — told The Associated Press late Monday that at least six pirates and two crew members had been killed.

He said two crew members also were rescued. It was not clear what had happened to the rest of the crew or what their nationalities were.

"We have rescued two foreign crews in the morning but our six comrades have unfortunately lost their lives," he said.

He said the ship had faced mechanical problems for months.

The EU naval force said that its maritime patrol aircraft have closed the sea area to search for any survivors.

Piracy was a growing problem off the Somali coast, fuelled by poverty and what some local people said was the need to stop international vessels from plundering fish stocks off Somalia. But armed guards aboard cargo ships and an international naval armada complete with aircraft that carry out onshore raids have put a huge dent in Somali piracy.

Somali pirates hijacked 46 ships in 2009 and 47 in 2010, according to the EU Naval Force. In 2011, pirates launched a record number of attacks — 176 — but commandeered only 25 ships, an indication that new on-board defenses were working.