Israel and Palestinian Islamist group Hamas still differ on terms for a Gaza ceasefire that Egypt is mediating, a Palestinian official familiar with the talks said on Wednesday.

Egypt has been trying to broker a truce to end violence that could derail US-backed peace negotiations between Israeli Prime Minister Ehud Olmert and Palestinian President Mahmoud Abbas.

The Palestinian official said Israel agreed to stop ground raids and air strikes in the Hamas-ruled Gaza Strip if fighters halted rocket attacks, but had not accepted demands to reopen the territory’s border crossings as soon as a ceasefire begins.

“Israel offered calm for calm, and said it would assess the situation and alleviate the blockade as calm prevails,” said the official, who declined to be identified.

He said Cairo would inform Israel of Hamas’ response later on Wednesday after mediators met leaders from the group in Egypt.

Egyptian airport sources said a Hamas delegation from Syria headed by Moussa Abu Marzouq, Hamas’ deputy leader in exile, had left Egypt without announcing a deal.

Gaza-based Hamas leaders were expected to continue talks on Wednesday night, and were to meet Egyptian intelligence chief Omar Suleiman. But the departure of Abu Marzouq cast doubt on prospects of an agreement.

Hamas, which seized control of the Gaza Strip last June, has offered a six-month halt to hostilities in the territory in return for an end to Israeli raids and the reopening of the border crossings.

In the latest violence in the Gaza Strip, an Israeli aircraft fired a missile at a car carrying a Hamas mortar crew.

They fled the vehicle before the projectile hit and were unhurt but five passersby were wounded, medical workers said.

Israel has also said a deal with Hamas must address the issue of a captive Israeli soldier. Hamas has said a truce agreement and the release of Gilad Shalit, held by Gaza fighters since 2006, should remain separate issues.

Arye Mekel, Israel’s foreign ministry spokesman, said Israel would offer no comment on the progress or contents of the talks.