The Israeli military will not let up on its campaign against Palestinian militants in Gaza until rocket attacks from the territory into southern Israel are ended, Prime Minister Ehud Olmert said Thursday.

"A war is going on in the south, every day, every night," Olmert said at an address to a business conference in Tel Aviv.

"This war will not stop. The moment will come when the scales will tip in this war and cause the firing in the south to be different from what it is today."

The military would continue to fight Hamas, Islamic Jihad and other militant groups linked to rocket attacks "without compromise, without concessions and without mercy," he added.

Israeli forces have killed at least 27 Palestinians since Tuesday in air strikes and gun battles with militants in the bloodiest fighting since Hamas took control of Gaza in June.

Air strike kills militant leader, wife: medics

On Thursday, an Israeli air strike destroyed a car in northern Gaza, killing a Hamas-allied militant leader and his wife, according to Palestinian medical officials. Two other Palestinians were reported injured in the attack.

Wednesday's deaths included three members of a Gaza family in what the Israeli military acknowledged was a missile attack on the wrong car.

Meanwhile early Thursday, Hamas claimed it fired 24 rockets at Israel after launching 79 rockets and mortars the day before. No injuries were reported.

The almost daily rocket attacks rarely strike their intended targets or cause casualties, but have kept residents in southern Israeli border towns such as Sderot under a constant state of fear.

The violence in recent days has threatened to derail peace negotiations between Israeli officials and a Palestinian negotiating team of Fatah members based in the West Bank. Hamas is not represented in the talks.

Palestinian negotiator Saeb Erekat said Thursday the raids on Gaza made it impossible to continue negotiations with Israel.

Hamas, which has been shunned by the international community since its victory in Palestinian parliamentary elections for its refusal to renounce attacks against Israel, has condemned President Mahmoud Abbas for taking part in the peace talks during the bloodshed.

The militant movement took control of the coastal strip following intense fighting with forces loyal to Abbas's Fatah faction, to which Abbas responded by dissolving the fractured Fatah-Hamas coalition government.

Speaking Wednesday from Damascus, Syria, exiled Hamas leader Khaled Mashaal told reporters that Israel's military actions in Gaza made Hamas less likely to negotiate any truce with the Jewish state or release Gilad Shalit, an Israeli soldier the group has held captive since 2006.

With files from the Associated Press