(Updates with Abbas-Haniyeh meeting postponed until Wednesday)

By Jeffrey Heller

JERUSALEM, May 22 (Reuters) - Israel said on Tuesday it could target Palestinian Prime Minister Ismail Haniyeh of Hamas and a Gaza ground offensive was possible unless world pressure was brought on the Islamist group to halt rocket fire.

The threat caused the postponement of a meeting between Haniyeh and President Mahmoud Abbas, who arrived in Gaza to discuss maintaining law and order and perhaps resuming a Gaza truce with Israel, an official from Abbas's Fatah movement said.

The official said the meeting would most likely take place on Wednesday. A meeting between officials from both sides to discuss similar issues was also called off because of Israel's threat against Hamas, he added.

At least 49 Palestinians have been killed in fighting between Hamas and Fatah since they formed a unity government in March, though a ceasefire declared on Sunday seems to be holding. The EU said it feared Gaza could slide into civil war.

Asked if Hamas's Haniyeh was on Israel's hit-list, Deputy Defence Minister Ephraim Sneh said: "I'll put it like this -- there is no one who is in the circle of commanders and leaders in Hamas who is immune from a strike."

Sami Abu Zuhri, a Hamas official, said in response in Gaza: "Any harm to Prime Minister Haniyeh or any Hamas leader would mean a change in the rules of the game and the occupation (Israel) must be ready to pay an unprecedented price."

U.S. State Department spokesman Tom Casey in Washington urged Israel to weigh the consequences "both in terms of the possibilities for continued political dialogue as well as what other kinds of reactions there might be".

Israeli Defence Minister Amir Peretz, meeting the European Union's foreign policy chief, Javier Solana, called on the international community to take action immediately to try to persuade Hamas to stop firing the makeshift rockets at Israel.

Abu Zuhri said Israel must first stop its attacks on Palestinians before the group and other factions could consider halting their own strikes.

The Israeli army said about 150 rockets have been fired from Gaza in a week in which Hamas, which had been battling Abbas's Fatah faction, turned to attacks against Israel, accusing the Jewish state of aiding its rival.

A woman was killed on Monday in the Israeli town of Sderot, the first fatality in a Palestinian rocket attack since November.

"There is no simple, single or simplistic response to the issue of the Qassam (rocket) fire," Israeli Prime Minister Ehud Olmert, in remarks broadcast on Tuesday, said during a visit to Sderot a day earlier, after the salvo.

Israeli air strikes over the past week have killed at least 34 Palestinians, medical officials said in Gaza. Militant groups said 23 of the dead were fighters.

INTERNATIONAL TEST

"Now this is a test for European diplomacy. It is a test for U.S. diplomacy. It is a test for the diplomacy of the free world. If the rockets do not stop, we will not stop," Peretz told reporters, with Solana at his side.

"We have been acting very, very patiently. We have been biting our lip and trying not to get to a situation whereby we have to enter into a wide-scale ground operation," he said.

An Israeli political source said Peretz was pressing for international action now, before Israel was forced to take "stronger action on the ground" in Gaza.

Hamas, which formed a unity government with Fatah in March, has lobbied for Western support while withstanding international pressure to recognise Israel and renounce violence, terms for a renewal of direct aid to the Palestinian Authority.

Hamas's armed wing said it launched several rockets into Israel on Tuesday. An army spokeswoman said 12 launchings had been spotted by military spotters.

In one Israeli attack on Tuesday, two missiles fired from an aircraft destroyed a post that Hamas's Executive Force militia had evacuated in the northern Gaza Strip, slightly wounding a passer-by, Hamas and local residents said. (Additional reporting by Nidal al-Mughrabi in Gaza, Dan Williams, Corinne Heller and Ori Lewis in Jerusalem, Wafa Amr in Ramallah and Arshad Mohammed in Washington)

AlertNet news is provided by