Fatah leader Mahmoud Abbas and Hamas leader Khaled Meshaal are in Cairo for reconciliation talks with Egyptian President Mohamed Morsi.
The visit will last several days, said Hamas politburo Vice President Moussa abu Marzook.
The Palestinian factions have been divided since the terrorist group seized control of Gaza after it routed Fatah in the 2007 Palestinian civil war that followed Hamas' parliamentary victory the previous year.
The leaders of the two Palestinian factions reportedly will meet with Egypt's intelligence chief before meeting with Morsi.
"We hope that Hamas might succeed in stabilizing its internal situation as the reconciliatory atmosphere seems stronger than ever, especially after it allowed a pro-Fatah rally in Gaza," Fatah's reconciliation leader Azzam Al-Ahmed told Egypt's Al-Ahram newspaper.
The event was intended to commemorate the 48th anniversary of Fatah's taking up arms against Israel.
The factions reached a deal in 2011 which would have paved the way for presidential and legislative elections last May, but it fell apart over who would head a transitional government.
Hamas leaders nixed another deal reached between Meshaal and Abbas in 2012, accusing Meshaal of making unilateral decisions without their support.
Israeli Prime Minister Benjamin Netanyahu said Wednesday that Israel would not cede any more land to the Palestinians, the Jerusalem Post reported.
"We see the dangers clearly," Netanyahu said. "Today Abu Mazen (Abbas) is in Cairo together with the head of Hamas. They are looking into a possible unity deal between Fatah and the terrorists who have been trying to annihilate the state of Israel, and who have fired rockets at our cities.
"We know that any territory we evacuate will be seized by Hamas and Iran, and we will not let that happen."