RAMALLAH, June 20: Palestinian President Mahmud Abbas on Tuesday called upon militants to immediately halt rocket attacks, as Israel threatened to wage a tougher response to an upsurge in cross-border violence.

He spoke just hours before Israeli aircraft attacked a car in the Gaza Strip the army said was carrying militants, killing three Palestinian children.

Israeli Prime Minister Ehud Olmert again vowed to strike at leaders of the ruling Hamas movement if the rocket attacks do not cease.

“There will be no immunity for those implicated in terrorism, no matter what they do or what movement they belong to,” Mr Olmert told the 35th World Zionist Congress meeting in Jerusalem.

The army said the militants targeted belonged to the Al-Aqsa Martyrs Brigades, an armed offshoot of Mr Abbas’s Fatah party, and they were implicated in planning attacks on Israel.

Palestinian sources said they escaped from the car.

A statement from Mr Abbas’s office said he ‘calls on all armed groups to cease firing rockets immediately and to fully respect the truce’ agreed by the main militant groups early last year.

“Any faction that does not respect the truce will bear the entire responsibility for the destruction and casualties that will result from an Israeli aggression against the Gaza Strip,” it added.

The statement was published as Mr Abbas prepared to hold his first meeting with Mr Olmert, on the margins of a conference hosted by Jordanian King Abdullah this week.

Israel earlier threatened a tougher response to persistent rocket attacks that have seen around 130 fired in the past 10 days alone, with Defence Minister Amir Peretz hinting he could order a massive military operation.

Mr Olmert has repeatedly called on Mr Abbas to dismantle armed Palestinian factions, including the armed wing of the now ruling Hamas, as a precondition to resuming stalled Middle East peace talks.

Medical and security sources in Gaza City said Tuesday’s Israeli air strike occurred between Gaza City and Jabaliya, just to the north.

Israel has castigated the moderate Abbas, who has been locked in a power struggle with the governing Hamas, for failing to tackle rampant insecurity in the Palestinian territories, where militants operate largely with impunity.

“The prime minister, the defence minister, others and myself have reached the conclusion no one will be protected if the... (rocket) terrorism continues,” the chairman of Israel’s parliamentary defence and foreign affairs committee, Tsahi Hanegbi, told public radio.

Mr Peretz, a resident of Sderot which has borne the brunt of the rocket attacks, has been criticised locally for failing to order a tougher military response, and has been raked over the coals by critics for his own lack of military expertise.

“Within a few dozen hours there is going to be a drastic change in the security issue, and none of the terror organisations are protected,” he was quoted as saying by local media late on Monday.

The mass-selling Yediot Aharonot newspaper also reported that chief of staff Dan Halutz and his deputy Moshe Kaplinsky have begun intensive talks on a possible large-scale operation in the Gaza Strip.

Israeli troops have so far refrained from full-on operations in Gaza since withdrawing from the territory last September after a 38-year occupation.

One rocket fell in open fields near Sderot, causing no damage or injuries on Tuesday. The radical Islamic Jihad claimed it fired four rockets. —AFP