Somali pirates hijack Libyan cargo ship

* MV Rim was flying North Korean flag

* Crew thought to be Romanians, Libyans

* Pirates say ship now docked in Puntland

(Adds ship's arrival in Puntland)

By Daniel Wallis

NAIROBI, Feb 4 (Reuters) - Somali pirates in the Gulf of Aden have hijacked a Libyan-owned cargo ship thought to be carrying 17 seafarers from Romania and Libya, a European Union anti-piracy force and a maritime group said on Thursday.

The number of piracy attacks worldwide leapt almost 40 percent last year, with gunmen from the failed Horn of Africa state accounting for more than half the 406 reported incidents, according to the International Maritime Bureau.

Kenya-based Ecoterra, which monitors shipping off Somalia, said the 4,800-tonne MV Rim was seized on Tuesday in the strategic channel south of Yemen. It said it was flying a North Korean flag, but was owned by White Sea Shipping of Tripoli.

"Her crew usually comprises 17 sailors and, based on outdated crew lists, it could be assumed that they are holding Romanian and Libyan nationalities," Ecoterra said.

The group said local reports suggested the hijackers were from Somalia's semi-autonomous northern region of Puntland.

"It is assumed the vessel is now commandeered to one of the Puntland pirate lairs," it said in a statement.

A pirate source confirmed that the ship had docked at Las Qoray in Puntland.

"The Libyan cargo ship has safely arrived at Las Qoray. We have been waiting for it and now we are on board. We shall be here with the ship for days," a pirate only known as Abdiqadir told Reuters.

A European Union counter-piracy force said a coalition ship, the USS Porter, and a helicopter from the USS Farragut confirmed the hijacking, but had no details on the make-up of the crew.

"The MV Rim ... has now altered course and is heading towards the Somali Basin. Coalition forces will now monitor the situation," EU Navfor said in a statement.

Typically, the heavily armed Somali pirates hold captured ships and their crews hostage until ransoms are paid.

Earlier this week, maritime officials and pirate sources said a ransom was paid for the release of a Marshall Islands-flagged cargo ship, the MV Filitsa.

As their ransoms demands spiral higher, rivalry between pirate gangs has grown. A dispute in January over the biggest ever payoff, for a Greek tanker carrying 2 million barrels of oil, triggered deadly gun battles at sea and then back on land.

The International Chamber of Shipping, which represents 75 percent of the global seaborne industry, said last month that it felt deepening frustration at the international community's "impotence" in combating increasing piracy in the Indian Ocean. (Additional reporting by Abdiqani Hassan in Bossaso; Editing by Giles Elgood)