Palestinian president Mahmoud Abbas and Hamas leader Khaled Meshaal will hold crisis talks in Saudi Arabia later today.
They will attempt to agree a deal to end the current struggle for power that has left scores dead.
A shaky ceasefire between Mr Abbas's Fatah and Hamas was holding in Gaza, where guns, mortars and grenades have fallen silent for the first time in days.
Around 100 people have been killed since the political tension boiled over into street fighting and tit-for-tat attacks in December.
The summit hosted by Saudi Arabia's King Abdullah in Mecca will seek to overcome deep-seated differences between the two factions on a power-sharing agreement and a national unity government.
Negotiators have tried but failed for months to find common ground on the key issues of ties with Israel and the division of portfolios in a unity accord that would seat Hamas and Fatah at the same cabinet table.
Hamas and Fatah have been at odds since the Islamists won a shock election victory in January 2006.
The Hamas government has resisted pressure to renounce violence, recognise Israel and abide by peace deals between the Palestine Liberation Organisation and Israel.
Excavation provokes anger in Jerusalem
Meanwhile, in Jerusalem, Israeli excavation work near an entrance to a compound in Jerusalem that houses the al-Aqsa mosque drew Palestinian protests and Israeli assurances the dig would not harm Islam's third holiest shrine.
Israeli police stationed reinforcements in the alleyways of Jerusalem's walled Old City to head off feared Palestinian violence at a flashpoint site at the heart of the Arab-Israeli conflict.
Israel's Antiquities Authority said it was searching for artefacts at the base of the compound known to Muslims as Haram al-Sharif and to Jews as Temple Mount before construction of a pedestrian bridge to replace a ramp leading up to the complex.
Bulldozers began breaking up parts of the pavement at the foot of the ramp, damaged by a snowstorm and an earthquake in 2004, to clear the way for what was described as a 'salvage excavation.'
Palestinian Prime Minister Ismail Haniyeh of Hamas said before leaving for the talks in Mecca that Israel was out to cause 'direct harm' to the al-Aqsa.
'I appeal to all our Palestinian people to be united and to rise up together to protect al-Aqsa and the holy sites on the blessed land of Palestine,' he said.
In Bethlehem, crowds of Palestinians threw stones at Israeli soldiers outside Rachel's Tomb, a holy site at the entrance to the West Bank city. The soldiers responded with tear gas.
Israel's opening of an entrance to an archaeological tunnel near Haram al-Sharif in 1996 touched off violent Palestinian protests and led to clashes in which 61 Arabs and 15 Israeli soldiers were killed.
