Pirates seized a fishing boat with a crew of 26 Taiwanese, Chinese and Vietnamese nationals off Madagascar in the Indian Ocean, the European Union naval forces said Thursday.

The Taiwanese vessel reported coming under attack on the morning of Christmas Day, December 25, some 120 nautical miles off the north-eastern tip of the island, the EU-Navfor anti-piracy mission said, adding that no contact has been possible since then.

"Strong indications are that FV Shiuh Fu No 1 has been pirated," it added in a statement. "The conditions of the crew or the vessel are not known."

The EU said there are now 26 vessels and 613 hostages being held by pirates.

The latest attack, following two further Christmas attacks even further south off central Mozambique in east Africa, underlines the extent to which international anti-piracy efforts, with China also cooperating with EU forces, have forced pirates to move further away from Somalia.