Special report: Palestine-Israel Conflicts          

    NICOSIA, Jan. 12 (Xinhua) -- A Greek-flagged vessel that set sail Monday afternoon for the war-battered Gaza Strip with medical supplies and pro-Palestinian activists on board had to return to Cyprus due to mechanical problems.

    The small boat "Spirit of Humanity," stopped three nautical miles (5.6 km) south of Cyprus after experiencing engine trouble, said Vangelis Pissias, the Cypriot coordinator on the vessel.

    More than 30 pro-Palestinian activists, doctors, aid workers and journalists were on the humanitarian mission organized by the U.S.-based Free Gaza Movement.

    Israeli authorities had warned that they would turn the boat back "by all means," according to Cypriot port officials.

    But Huwaida Arraf, spokeswoman for the Movement, said they would not be deterred by the threats.

    The activists have to wait in the southeastern Cypriot port city of Larnaca until their boat is repaired.

    In a previous failed mission on Dec. 30, 2008, the movement's chartered boat "Dignity" was rammed "deliberately, repeatedly and without warning" by an Israeli gunboat, and forced to seek haven in a neighboring port in Lebanon.

    Before Monday's voyage, the organizers had sent an official notification to Israel's foreign affairs and military authorities, declaring that the boat "Spirit of Humanity" will be sailing from Cypriot waters into international waters, then directly into the territorial waters of the Gaza Strip without entering or nearing Israeli territorial waters.

    Between August and December 2008, the Free Gaza Movement successfully challenged the Israeli blockade five times, bringing humanitarian supplies to the besieged Gaza Strip.