London/Nairobi, April 20 (DPA) Somali pirates have seized three Thai fishing vessels with 77 crew on board almost 2,000 km off the coast of Somalia, the furthest-ranging attack to date, the European Union naval force said Tuesday.

Pirates have not been deterred by an increase in international patrols off the coast of Somalia, instead moving further out into the Indian Ocean.

The EU’s anti-piracy force EU NAVFOR said in a statement that the MV Prantalay 11, MV Prantalay 12 and MV Prantalay 14 – all belonging to Thai-based company PT Interfishery Ltd – were taken Sunday.

The crew are safe and the ships are headed for the Somali coast, EU NAVFOR said.

Pirates seized the ships almost 1,000 km outside EU NAVFOR’s patrol area, which the force said proved its mission was working.

“It is a clear indication that the EU anti-piracy mission, together with those of NATO and CMF (Combined Maritime Forces) is having a marked effect on pirate activity in the area,” EU NAVFOR said in a statement on its website.

International warships began operating off Somalia at the end of 2008 to combat a surge in attacks on ships passing through the Gulf of Aden – one of the world’s busiest shipping corridors.

Somali pirates can command millions of dollars in ransom money for each ship seized, something analysts say means they are unlikely give up the lucrative business.

The lawless Horn of Africa nation has been without a functioning central government since 1991, making it almost impossible to tackle piracy on land.