After a first day of dialogue to end factional fighting, Palestinian militants have been told to reach agreement over a peace plan with Israel or face a referendum on it.
President Mahmoud Abbas gave his own Fatah group and the Hamas movement of Prime Minister Ismail Haniyeh ten days to agree on a proposal to recognise Israel.
The conference, involving a video link between Ramallah and Gaza, is aimed at ending a bloody feud between the two sides.
The proposal was drawn up by senior figures from Hamas, Fatah and the Islamic Jihad group who are in prison in Israel. It calls for a negotiated settlement with Israel if it withdraws from West Bank land occupied since 1967.
The challenge from Abbas took many by surprise, coming on the first day of talks.
Tensions are soaring in the West Bank and Gaza after a week of clashes which have claimed around ten lives.
The proposal also calls for a unity government incorporating the two factions.
Some Hamas officials said they did not object to the idea of a referendum but criticised Abbas for setting conditions before the end of discussions.