Somali pirates have released a Spanish Fishing Vessel and its 36 crew, which was seized more than six weeks ago and at the same time, captured a Virgin Islands owned Chemical Tanker with 28 North Korean crew.

According to Spanish Prime Minister Jose Luis Rodriguez Zapatero, pirates freed the vessel, MV Alakrana late on Tuesday and that is now sailing in safe waters with all its unharmed crew members on board.

"I can confirm that the Alakrana fishing trawler is sailing freely towards safer waters and that all of its crew members are safe and sound," he told a news conference.

Reports say the release of the vessel, which was surrounded by controversy, was facilitated by ransom payment of about $3.5 million.

Pirates have earlier demanded ransom and release of two of their comrades seized by Spanish navy.

However, Spanish PM did not mention the payment of any ransom in exchange for the release of the trawler.

On the other hand, a Virgin Islands owned chemical tanker, MV Theresa VIII was captured south of Somali waters, 180 nautical miles North West of the Seychelles.

"a Virgin Islands owned (operated from Singapore) Chemical Tanker named the MV Theresa VIII was hijacked in the south Somali Basin, 180 nautical miles North West of the Seychelles," said a statement from EU naval force.

The 22,294 tonnes vessel was end route to Kenyan port of Mombassa but now has turned course and is heading to the north towards Somali waters, it added.