Israel threatened tougher action against rocket fire from the Gaza Strip on Sunday as the territory's sole power plant again shut down in the face of a crippling blockade. Outgoing Prime Minister Ehud Olmert said he has told security chiefs to draw up contingency plans for military action against militant groups in Gaza, although there have been no deaths as a result of the rocket and mortar fire of the past week - and Israel initiated the latest flare-up with a deadly invasion of the enclave in early November.

"The State of Israel does not intend to show restraint over this, nor will it countenance such a situation," his office quoted him as telling the weekly cabinet meeting.

Foreign Minister Tzipi Livni said the government should respond "militarily, economically and politically."

"The truce has not been respected by the other side," she claimed, referring to an Egypt-brokered cease-fire with the Islamist Hamas which controls Gaza that went into force on June 19. "They are firing on our citizens. That is enough."

The government has decided to allocate $250 million next year for the construction or completion of shelters in 8,500 houses within 8 kilometers of the Gaza Strip, according to an official statement.

Israel kept its borders with Gaza closed on Sunday as a rocket and two mortar rounds were fired from the territory. There were no casualties or damage from the attacks, an army spokesman said.

On Saturday one Palestinian resistance fighter was seriously wounded in an Israeli air strike in northern Gaza, medical sources and the military said.

Israel has allowed food or fuel into the aid-dependent territory on only four days in as many weeks and a lack of diesel again forced the shutdown on Sunday of its sole power plant, electricity authority deputy director Kanaan Obeid told AFP.

Hamas spokesman Fawzi Barhum accused "the Zionist enemy of continuing its aggression against Gaza by systematically violating the terms of the truce." "Discussions have taken place recently with the various parties about the truce but it seems difficult to agree an extension and Hamas is ready for all eventualities," he told AFP.

The truce expires on December 19.

Israel had been supposed to relax its blockade of Gaza - in place since Hamas won democratic elections in early 2006 and tightened after its members routed security forces loyal to Western-backed President Mahmoud Abbas in June 2007 - as part of the deal but failed to honor its commitment.

In a report published on Sunday, the Israeli daily Yediot Ahronot calculated that at least 215 rockets fired from the Gaza Strip have hit Israel since November 4, when Defense Minister Ehud Barak ordered a tightening of the blockade after militants retaliated for a raid that killed seven Hamas men by lobbing several projectiles at the Jewish state.

The minister has previously said a large-scale military operation against Gaza is "inevitable" although he said on Sunday that any such action should be "carefully weighed" before being launched "at the right moment."

In what was a goodwill gesture to Abbas, whose effective control extends only to the Occupied West Bank, an Israeli Cabinet committee gave its approval to a list of 230 Palestinian prisoners to be freed this week.

The prime minister's office said none of the 230 were implicated in deadly attacks against Israelis. It did not explain why the figure was put at 230 instead of the 250 promised last week.

Israeli security forces, meanwhile, boarded a boat in the port of Jaffa to prevent a bid by Palestinian-Israeli MPs to deliver aid to Gaza in defiance of the crippling blockade.

"We were preparing to set sail for the Gaza Strip to deliver hundreds of kilograms of medicines and basic goods and the maritime police stopped us weighing anchor," said MP Ahmad Tibi.

"Israeli authorities allow the settlers to do what they want to the Palestinians in the West Bank but at the same time they stop us from providing humanitarian assistance to the Gaza Strip," he added. "We remain determined to provide it."