(CNN) -- Pirates in the Indian Ocean captured Saturday a general cargo ship and its 27-member Thai crew, the European Union Naval Force Somalia said.
Twenty-five vessels and 601 hostages are now being held by pirates in the region, officials said in a statement.
The Thai MV Thor Nexus was hijacked about 450 nautical miles northeast of the island of Socotra, officials said.
The ship was on its way to Bangladesh from Jebel Ali in the United Arab Emirates. No details of the attack were known Saturday.
Pirate attacks and subsequent ransoms have become a frequent hazard for sailors off Somalia, which has had no effective central government since 1991.
Pirates on Monday hijacked another cargo ship, officials said. The attack happened about 400 nautical miles northeast of the Seychelles.
At least four pirates, using two small boats and rocket-propelled grenades, boarded the MV Orna, a Panama-flagged merchant vessel owned by a United Arab Emirates company.
The European Union Naval Force Somalia is a multinational task force with the mission to escort merchant vessels carrying humanitarian aid of the World Food Programme and vessels of the African Union Mission in Somalia.