An unmanned Palestinian fishing boat exploded off the coast of the Gaza Strip on Monday in an apparent attempt to hit naval patrols in the area, the Israeli military said, reporting no casualties.

An army spokesman said the nearest Israeli vessel was "a safe distance" from the Palestinian boat when it blew up about 300 metres off the northern Gaza shore near the border with Israel.

The explosion was heard further along the coast in Gaza City, several miles to the south. Local Palestinian media did not immediately report on the incident, and no groups claimed responsibility for the blast.

In 2002, two Palestinian militants on an explosive-packed boat blew themselves up next to an Israeli patrol vessel, killing themselves and wounding four naval crewmen. Islamic Jihad, a violent group backed by Syria and Iran, claimed responsibility at the time.

The Israeli navy closely monitors the coastal strip as part of a general blockade, tightened since the Islamist Hamas group took control of Gaza in June 2007. Patrol boats are particularly on the lookout for attempts to smuggle in arms and explosives.

Israel launched a 22-day offensive into Hamas-controlled Gaza in late December to halt rocket fire at Israeli targets and the smuggling of arms in the strip. The weapons typically make their way into Gaza through underground tunnels along the Egyptian border.

Egyptian authorities, however, have alleged the weapons reach Gaza by the sea.

In January, the U.S. Navy intercepted a Cypriot-flagged ship suspected of transporting explosives from Iran bound for Gaza. The vessel and its cargo were escorted to Cyprus, where they were impounded by authorities.

In February the Israelis intercepted a ship carrying humanitarian supplies and rights activists from Lebanon to the Gaza Strip, towing the vessel to an Israeli port, deporting those on board and delivering the supplies to Gaza by land after a rigorous inspection.