The two main rival Palestinian factions began a new round of talks in Cairo on Sunday, facing a 10-day deadline for a reconciliation agreement, Egypt's official MENA news agency reported.
"The two delegations, who had a working dinner on Saturday evening, met (on Sunday) for a sixth round of talks," MENA reported.
Cairo has been mediating talks between president Mahmud Abbas's Fatah party and the Islamist Hamas movement aimed at healing bitter divisions between the two since Hamas seized control of the Gaza Strip in 2007.
The factions will also meet Egypt's intelligence chief Omar Suleiman ahead of a July 7 target date to sign an agreement which will lay out an electoral law, define the make-up of security forces and of a committee to liaise between the Gaza Strip and the West Bank ahead of an election in 2010.
Smaller Palestinian factions will join the talks on July 5, senior Fatah official Nabil Shaath told AFP.
Shaath said disagreements arose in Sunday's talks, with Hamas insisting on discussing political prisoners before other issues on the agenda but he added that a special committee was working on resolving the problem.
Hamas has demanded that Abbas's Palestinian Authority release all "political prisoners" -- referring to the scores of Hamas members arrested in the Israeli-occupied West Bank -- or provide a timetable for their release.
"Any hope of reaching an agreement on July 7 basically depends on how Fatah deals with the issue of political prisoners," Omar Abdelraziq, a senior Hamas official in the West Bank, told AFP on Saturday.
The Islamist movement has released 20 Fatah members in Gaza, "to aid Egyptian efforts toward bringing about national reconciliation," Hamas government spokesman Taher al-Nunu said on Sunday.
Fatah and Hamas have accused each other of persecuting their rivals in the territories under their control, and both groups have been accused by human rights groups of arbitrary arrests and mistreatment of detainees.
Both groups deny they make political arrests, saying the detentions are conducted on security grounds.