Israeli forces have shot dead four Palestinians on a vessel off the coast of Gaza.

Israeli helicopters and naval forces attacked the boat off the coast of Nusseirat in the early hours of this morning.

Two hours later, four bodies in diving suits were pulled from the water and taken to hospital, medical sources and witnesses said.

Israel described the dead men as 'commandos'.

Searches are under way for another two people still believed to be missing.

The Israeli military said a naval force in the area had attacked a boat carrying 'a squad of terrorists wearing diving suits on their way to execute a terror attack'.

Speaking to AFP, survivor Abu al-Walid said there were seven unarmed men on board, all from the al-Aqsa Martyrs' Brigades, an armed group which is loosely tied to the Fatah movement of Palestinian president Mahmud Abbas.

'We were doing some regular training along the Gaza coast,' he said. 'During the early morning, we were surprised by dozens of naval boats which opened fire and began shelling us. Four of our people were killed, two of us escaped and one is still missing.'

Mr Walid said there were 'no arms in the boat,' and that the group had been engaged in 'swimming training' at the time of the attack, which took place about 100 metres off the shore.