Rival Palestinian leaders have failed to resolve their differences over a controversial planned referendum.
The PM talks of the "dangers" of the president's plan
Palestinian Authority President Mahmoud Abbas met Prime Minister Ismail Haniya late on Saturday to discuss the poll, which Mr Abbas has called for 26 July.
Palestinians will vote on a statehood plan that implicitly recognises Israel, whose right to exist Hamas rejects.
After the talks Mr Abbas restated his commitment to a vote and Mr Haniya said it would endanger Palestinian unity.
On Saturday, leading Hamas official Mushir al-Masri denounced the proposed referendum as nothing short of a "a declaration of a coup against the [Hamas-led] government".
More talks are expected on Sunday.
Mr Abbas and Mr Haniya met for late-night talks on Saturday, following the highly charged funerals of seven members of a family killed by the shelling of a Gaza beach on Friday. Palestinians blame the deaths on Israel.
President Abbas says the referendum will promote unity
"We failed to agree on the referendum question and we stressed to the president the dangers of this consultation for Palestinian unity," Mr Haniya said following the meeting, according to AFP news agency.
A spokesman for Mr Abbas said he had insisted the referendum would go ahead.
Mr Abbas has given Hamas an ultimatum - accept the statehood plan, or the Palestinian people will be asked to approve it directly.
He says it is needed because Palestinian political parties have reached a deadlock over how to approach Israel.
The 18-point plan was drawn up by Palestinians from various factions who are serving time in Israeli prisons.
It sets out formal Palestinian claims to an independent state on land occupied by Israel in 1967 - implicitly adopting a two-state solution, and thus recognising Israel's right to exist.
Tensions between Fatah and Hamas have spilled into violence
It also calls for an end to attacks against Israel within those recognised borders, and would call for establishment of a Palestinian government of national unity.
Hamas refuses to recognise Israel or renounce violence - a stance which prompted the US and European Union to halt funding to the Palestinian people after Hamas took office in March.
The situation reached crisis point in May, as more than 150,000 government workers struggled to survive without pay and the tensions between Hamas and Mr Abbas's Fatah party spilled over into clashes in which several people have been killed.
Towards unity - or war
Announcing the date of the referendum on Saturday, Mr Abbas said Palestinian suffering was "increasing day by day".
He said time was "a sword against Palestinians' throats" and that as dialogue had broken down between Palestinian political parties, the people should now decide the best way forward in dealing with Israel.
But Hamas has denounced the referendum as illegal and sees it as a power grab by Fatah, which was trounced in January elections.
It warns that far from having a unifying and healing effect on Palestinian society, the referendum will cause deep divisions.
Our correspondent in the West Bank, Katya Adler, says some people there warn the referendum could even spark a civil war.