Fatah and Hamas have begun talks aimed at reconciliation in Cairo.
Chief Egyptian mediator, intelligence chief Omar Suleiman, says the meeting must lead to a unity government.
He says there might not be another chance to reconcile the two rival Palestinian factions.
Hamas won an election for the Palestine Authority in January 2006 and gained control of Gaza in June 2007 after continued fighting with Fatah.
The BBC reports efforts to secure a reconciliation have gained strength since a military offensive by Israel in Gaza, which ended on 18 January.
Fatah and Hamas have fundamental differences over how to deal with Israel.
While Fatah has renounced violence, Hamas refuses to recognise Israel. Hamas is prepared to accept a short-term truce, but reserves the right to fight Israel.