Nidal al-Mughrabi

GAZA, June 26 (Reuters) Palestinian officials today said they were trying to locate an Israeli soldier believed to have been abducted by Gaza Strip gunmen in a border raid that prompted Israel to threaten a major military offensive.

Israeli Prime Minister Ehud Olmert's inner cabinet gave the Palestinians 48 hours to return Corporal Gilad Shalit after he went missing in yesterday's unprecedented attack on a frontier post by militants including members of the ruling Islamist Hamas.

With Israel vowing reprisals that could include re-invasion of Gaza, a coastal territory it quit last year after 38 years of occupation, the Hamas-led Palestinian government and more moderate President Mahmoud Abbas called for Shalit's release.

Palestinian security officials said there were negotiations with a group of gunmen that claimed responsibility for the border raid, though they have not confirmed holding Shalit.

''We are continuing our efforts to release the kidnapped soldier,'' said one mediator on condition of anonymity. ''As of now, we have been told that the soldier is fine. He is in good condition and he is being treated well.'' Olmert held both Hamas and Abbas responsible for the raid, setting back expectations that Israel could revive peacemaking by talking to the Palestinian president and circumventing the hardline government with which he shares power.

''We hold Abu Mazen (Abbas) responsible. He holds ultimate responsibility for what goes on,'' Justice Minister Haim Ramon told Israel Radio.

Egyptian emissaries were helping efforts to defuse the crisis, which has called into question Olmert's plan to withdraw unilaterally from parts of the West Bank, the other territory the Palestinians want as part of a state.

SWAP RULED OUT Hamas and other militant groups spearheading a more than 5-year-old Palestinian revolt have said in the past they would kidnap Israelis to try to gain the release of thousands of comrades imprisoned in the Jewish state.

Israeli officials ruled out any such swap for Shalit, a 19-year-old conscript tank gunner.

''We are dealing with bringing Gilad home. We have no intention with negotiating with Hamas on a prisoner exchange,'' Ramon said, adding that Israel also believed the soldier was alive though he may have been wounded.

Under pressure from Israel's rightist opposition parties opposed to ceding occupied land to the Palestinians, Olmert has pursued tough action against Gaza militants despite an outcry over the killing of 14 bystanders in recent Israeli air strikes.

Israeli officials have hinted that should the deadline for Shalit's release go unmet, there could be an aerial blitz on Gaza targeting both civilian infrastructure and Hamas leaders including Palestinian Prime Minister Ismail Haniyeh.

Israeli troops and armour have also been massing on Gaza's borders. Ramon said that an incursion, if ordered, would not constitute a reoccupation of the cramped and impoverished strip.

''When we go in, this operation, even if it lasts more than a couple of days, will not last for years. It will be purely military,'' he said. ''We left Gaza, we are not there. There is no reason for anyone in Gaza to act against Israel.'' Reuters SI VA DS1240