SOFIA, Dec. 29 (Xinhua) -- There were five Bulgarian sailors onboard the UK-flagged chemical tanker St James Park seized by Somali pirates on Monday, Bulgarian officials said on Tuesday.

"Five men among the 26 crew members of St James Park are Bulgarians," captain Prodan Radanov, the head of the Bulgarian office of the ship manager, Zodiac Maritime Agencies, told reporters.

The Bulgarian sailors are between 34 and 46 years old, four of them living in Varna and one in Ruse. Their families were informed about the incident, Radanov said. One of the Bulgarian sailors is a chief officer of the ship, he added.

According to Radanov, the Bulgarians joined the crew on different dates between October and Dec. 19, 2009.

The Bulgarian Ministry of Foreign Affairs has been working on this case since Monday, Ministry Spokesman Dragovest Goranov told reporters. All International Bulgarian partners, including the European Union, were informed, Goranov said.

This is the second incident this year in which Bulgarian sailors were kidnapped by pirates. In April cargo ship Malaspina Castle with 16 Bulgarians on board was captured in the Gulf of Aden, and about one month later the ship was released after a ransom payment. All 24 crew members were in good health after the incident.