A Hamas source said that the talks between Azzam al-Ahmed, the chief of Fatah's parliamentary bloc, and his Hamas counterpart, Mahmud al-Zahar, were initially to be held on Wednesday night, but were put off for "technical reasons".
Al-Ahmed had earlier confirmed that the second set of talks in two weeks would be to "discuss the forming of a government".
Hamas spokesman Salah al-Bardawil said al-Ahmed had arrived in Gaza City for what would be the second such meeting in as many weeks.
Al-Bardawil said Hamas representatives were to also meet Mahmoud Abbas, the Palestinian Authority president, on Thursday.
"The international community should support the Palestinian people and continue its aid in all forms, and not punish them or starve them because of their democratic choices"
The talks between al-Ahmed and al-Zahar were to come three days after a heated first working session of the new Hamas-dominated parliament, when the chamber repealed a series of measures passed by the outgoing Fatah-led house.
Fatah MPs left the parliament in protest and later lodged an appeal against the vote with the Palestinian high court.
Don't punish Palestinians
As the two sides readied for talks, Abbas called on the world not to punish the Palestinians for electing Hamas and to continue providing them with aid.
"The international community should support the Palestinian people and continue its aid in all forms, and not punish them or starve them because of their democratic choices," Abbas said after a meeting in the West Bank town of Ram Allah with Janez Drnovsek, the president of Slovenia.
Abbas said the international community "needs to be patient and give Hamas a chance. We cannot force them to make a 180-degree turn".
He also called on the international community to step up its efforts to "relaunch the peace process and negotiations toward application of the road map" peace plan.
The internationally drafted road map, launched nearly three years ago, envisions an independent Palestinian state living in peace alongside a secure Israel.