Delegates from both Fatah and Hamas met "to prepare for the comprehensive dialogue" which is to take place on Tuesday in the Egyptian capital, Azzam al-Ahmed, head of the Fatah delegation told AFP.
Hamas chief Khaled Meshaal was expected to arrive in Cairo late on Monday, with Palestinian president and Fatah chief Mahmud Abbas set to join him on Wednesday, officials said.
The two were to hold talks on Thursday to discuss ways of implementing a landmark reconciliation deal between their rival movements which was signed in May but which has never got off the ground.
The deal called for the establishment of a caretaker cabinet which would prepare for legislative and presidential elections within a year, but it was never implemented due to disagreements over who would take on the role of premier.
Sunday's dialogue between the two movements was expected to continue until Tuesday when they would be joined by representatives of all the other Palestinian factions to pin down plans to hold general elections in May and to discuss reforming the Palestine Liberation Organisation (PLO).
Ahmed said Tuesday's meeting "will focus on different points of the reconciliation agreement signed in May, the PLO, the formation of government, elections, reconciliation and the unification of the security forces and of civil institutions and security."
On Thursday, there will be a meeting of the Palestinian National Council (PNC) which will discuss allowing Hamas and Islamic Jihad to join the PLO, he said.
Hamas and Fatah officials were also expected to discuss the release of political prisoners held by both sides, which both parties have pledged will take place soon. Abbas and Meshaal last met on November 24 in Cairo after which they announced that they had ironed out their differences and begun a new era of "partnership" that would make good on the unity deal
Hamas and Fatah, which respectively control Gaza and the West Bank, have long been political rivals. Tensions spilled over into deadly violence in 2007 when Hamas forced their Fatah rivals out of Gaza and took control of the strip.