A chemical tanker with a crew of 28 North Koreans has been hijacked by pirates in waters off Somalia, the EU’s naval force (Navfor) says.

The MV Theresa VIII, a Singaporean-operated tanker, was taken on Monday in the south Somali Basin, 180 nautical miles north-west of the Seychelles.

It had been heading for Mombasa, Kenya, but was diverted north, Navfor said.

Meanwhile, pirates holding a Spanish trawler say they are freeing it for a ransom of at least $3.5m (£2.1m).

The Alakrana, a tuna boat, was hijacked last month along with its crew of 36, including 16 Spaniards, eight Indonesians and others from Ghana, the Ivory Coast, Madagascar, Senegal and the Seychelles.

The trawler, which is based in the Spanish Basque Country, was seized 400 nautical miles north-west of the Seychelles island of Mahe, according to coast guards.

Somali pirates, using “mother ships” to launch their small-boat attacks on vessels, have extended their range to an area off the Seychelles in recent months in order to evade the navies patrolling the Horn of Africa.

Pirates driven off

The MV Theresa VIII, the owner of which is based in the Virgin Islands, is a tanker of 22,294 deadweight tonnes, said Navfor, the EU naval force operating in the region to protect shipping.

It has emerged that guards aboard a Ukrainian cargo ship, the MV Lady Juliet, successfully fought off pirates in the Gulf of Aden on Monday.

Pirates firing Kalashnikov assault rifles and rocket-propelled grenades approached the vessel from their mother ship but came under return fire from a Navfor detachment protecting the ship.

Navfor supplies vulnerable ships with armed guards under certain circumstances.

Nobody was hurt aboard the Lady Juliet, which bears a St Vincent and The Grenadines flag, and any casualties among the pirates could not be confirmed.

More than 10 ships and 200 hostages are currently being held by pirates operating in waters off Somalia.

Many of the pirates began as fishermen and say they are stopping illegal foreign fishing boats stealing Somali fish, BBC international development correspondent Mark Doyle reports.

The upsurge in piracy in the region is a consequence of the failure to find a solution to Somalia’s political disputes, our correspondent notes.

The weak central government faces an Islamist insurgency and parts of the country have broken away to form autonomous regions