ANKARA, Turkey -- A lone hijacker claiming to have a bomb have hijacked a ferry off the western port city of Izmit with some 20 passengers on board on Friday, an official said.

Ibrahim Karaosmanoglu, mayor for Izmit, told NTV television that the man claimed that there were four other hijackers on board the Kartepe ferry. But the mayor said crew told him the hijacker was alone.

There was no information on his identify or his motive.

Karaosmanoglu said the man was demanding to speak to the media.

State-run TRT television said coast guard boats were shadowing the ferry as it was sailing off the coast of the town of Yalova in the Sea of Marmara, which connects the Black Sea to the Aegean.

NTV television said there were some 20 passengers and four crew on board.