A Palestinian fighter has been killed in an accidental bomb explosion in the northern Gaza Strip, according to the ruling Hamas faction.

Three members of Hamas's armed wing were also injured in the blast which occurred as a result of mishandling of explosives, the group said in a statement, according to the AFP news agency.

Hamas had initially said the explosion was caused by Israeli shelling, but an Israeli military spokeswoman denied any involvement in the blast, saying "there were no actions by our forces in the area".

Gaza, where Israel waged a three-week war a year ago, has seen a flare-up of violence in the last week with Israeli air strikes and Palestinian rockets.

Israel said Palestinian fighters other than Hamas were responsible for the recent rash of cross-border rocket and mortar attacks, and urged Hamas to rein them in.

Ehud Barak, Israel's defence minister, urged Hamas on Monday to rein in other armed groups in the territory, or face Israeli action.

"I think the recent days reflect the inability of Hamas to control the dissident groups, the Popular Committees or Islamic Jihad, who are trying to break the tranquillity," Barak told the Reuters news agency during the unveiling of an Israeli anti-rocket system due to be deployed outside the Gaza Strip by June.

"Hamas is well deterred from trying another direct collision with Israel. I hope that they will take over - or else," Barak, asked if a new Gaza war was possible, said.

Asked about Barak's comments, Sami Abu Zuhri, a Hamas official, said the Palestinian attacks were carried out in response to "continued Israeli aggression".

A Palestinian official, who asked not to be identified, said Hamas planned to meet other groups soon to urge restraint, unless Israel stepped up its attacks.