* Bitter rival Hamas says Abbas didn't tell them his plans
* Past attempts to form unity administration futile
* Hamas, Abbas's Fatah split over conflict with Israel
Palestinian President Mahmoud Abbas said on Saturday he would begin talks with rival factions including Islamist Hamas to form a unity government, a crucial step towards healing years of damaging internal divisions.
But, underscoring the chasm between Abbas's Fatah movement and Hamas, Hamas spokesman Sami Abu Zuhri said Abbas had not consulted his group about his move and the Islamists had only heard about it in media reports.
Hamas and Western-backed Abbas, who heads the more secular Fatah that holds sway in self-rule areas of the Israeli-occupied West Bank, have been at loggerheads since Hamas seized the Gaza Strip in a brief civil war in 2007.
Past unity attempts have foundered because Hamas and Fatah have been unable to agree a joint agenda, above all on how to handle the conflict with Israel. Hamas is committed to Israel's destruction while Fatah supports a negotiated solution providing for a Palestinian state co-existing alongside Israel.
The need to form a new administration was prompted by the resignation earlier this month of Prime Minister Salam Fayyad because of a rift between him and Abbas and it has created an opportunity for Abbas to forge a unity government.
Abbas published a statement on the Palestinian official news agency, WAFA, on Saturday urging factions "to cooperate" with his effort to form a national unity government that would be charged with readying presidential and parliamentary elections.
Hamas and Fatah have repeatedly failed to bridge their political differences despite signing an Egyptian-brokered reconciliation agreement in 2011. There have been no substantive moves to implement the accord.
Hamas rejects the interim peace accords which Fatah leaders signed in the 1990s with Israel. Peace talks between Israel and Abbas have been stalled since 2010 over Israeli settlement expansion in the West Bank.
Wasel Abu Youssef, a member of the Palestine Liberation Organisation (PLO), the Palestinians' highest decision-making body led by Abbas, said Palestinian basic law required forming a new administration because of Fayyad's resignation.
"Abbas's step has thrown the ball into Hamas's court to agree on a date for holding elections and they will be responsible for the failure if they do not accept," Abu Youssef told Reuters.
Abu Zuhri said holding elections was not possible under the current circumstances in the West Bank because Israel maintained overall control of the territory and Fatah continued to arrest Hamas men and curb their freedoms.