CAIRO - Egyptian President Abdel Fattah al-Sisi promised Israel on Tuesday warmer ties if it accepts efforts to resume peace talks with the Palestinians, urging Israeli leaders not to waste an opportunity to bring security and hope to a troubled region.

In an impromptu speech at an infrastructure conference in the southern city of Assiut, Sisi said his country was willing to mediate a reconciliation between rival Palestinian factions in an effort to pave the way toward a lasting peace accord with the Israelis.

"If we are able to solve the issue of our Palestinian brothers it will achieve warmer peace ... I ask that the Israeli leadership allow this speech to be broadcast in Israeli one or two times as this is a genuine opportunity," Sisi said.

"I say to our Palestinian brothers, you must unite the different factions in order to achieve reconciliation and quickly. We as Egypt are prepared to take on this role. It is a real opportunity to find a long-awaited solution."

French President Francois Hollande said on Tuesday an international conference due in late May in Paris to relaunch peace talks between Palestinians and Israelis had been postponed but would take place this summer.

Prime Minister Benjamin Netanyahu told France's foreign minister on Sunday that Israel remained opposed to a French initiative for an international conference to try to revive peace talks .

Egypt was the first of a handful of Arab countries to recognise Israel with a US-sponsored peace accord in 1979, but Egyptian attitudes to their neighbour remain icy due to what many Arabs see as the continued Israeli occupation of land that is meant to form a Palestinian state.

A conference on the peace process between Israelis and Palestinians, due to be held on May 30 in Paris, has been postponed, French President Francois Hollande said Tuesday. "(US Secretary of State) John Kerry cannot come on May 30 so it has been delayed. It will take place in the summer," he told French radio.

Hollande said it was vital for France to take "a strong initiative" in the dispute. "If not... what will happen? Settlement building, attacks," he said.

The original date for the conference falls on the US Memorial Day holiday honouring members of the armed forces who died in combat.

"We're in discussions right now with the French about any possible alternative date that might better work for the secretary," State Department spokesman John Kirby said Monday, though he added that Kerry's agenda was currently "jammed".

French Foreign Minister Jean-Marc Ayrault was in Jerusalem and Ramallah on Sunday to present the French peace initiative to Israeli Prime Minister Benjamin Netanyahu and Palestinian president Mahmud Abbas.

Ayrault received support from the Palestinians but objections from Israel. Netanyahu questioned French "impartiality" after Paris voted in favour of making Palestine a UNESCO member five years ago.

"We are going to work with all the actors, the big countries and neighbouring nations, to create the parameters that will allow the Israelis and Palestinians to return to the negotiating table," Hollande said Tuesday.

Hamas spokesman Sami Abu Zuhri said on Twitter that Hollande's announcement of the delay was "further evidence of the failure of the (peace settlement) option and the project of (Palestinian president) Mahmud Abbas".

A staunch ally of Israel, Washington has traditionally brokered direct talks between the Israelis and Palestinians and played down multilateral initiatives, especially within the United Nations.

The United States has regularly called for a "two-state solution" to the Middle East crisis since the last US-brokered talks collapsed in April 2014.

The Palestinians plan to submit a UN Security Council resolution condemning Israeli settlements in the West Bank, but previous attempts have met with a US veto.