Pirates on Friday hijacked a Spanish fishing vessel in the Indian Ocean about 600 km off the Somali coast, Basque regional agriculture and fishing official Pilar Unzalu said.
MS Alakrana, which is based in the Basque port of Bermeo, informed another fishing boat of its situation, following which the European Union's Operation Atalanta launched a security operation.
Two Luxembourg planes flying over the vessel observed armed people on board.
The company which owns the Alakrana said it had been unable to contact the 36-member crew, which comprises 16 Spaniards, eight Indonesians, four Ghanians, three Senegalese as well as two people from Ivory Coast, two from Madagascar and one from the Seychelles.
Sources of the Basque tuna fish sector said the Alakrana was hijacked in international waters and was being taken towards the Horn of Africa country.
On September 4, the Alakrana managed to escape from would-be hijackers.
Josu Erkoreka from the Basque Nationalist Party (PNV) criticised Defence Minister Carme Chacon for not placing Spanish marines on board Spanish vessels fishing in the Indian Ocean.
Prime Minister Jose Luis Rodriguez Zapatero's Socialist Party rejected the accusations, saying such a measure was not judicially possible.
Nearly 20 Spanish fishing vessels were in the same area as the Alakrana at the time of the hijacking.