Vatican City (AFP) - Israeli President Shimon Peres and Palestinian leader Mahmud Abbas called for peace on Sunday at an unprecedented prayer with Pope Francis on Sunday amid heightened tensions between the two sides.

Peres said peacemaking was a "duty" and a "holy mission" at the spiritual event in the Vatican Gardens, and Abbas called for a "comprehensive and just peace" that could bring stability to the Middle East.

Joined by the Orthodox Patriarch of Constantinople Bartholomew I, the three spoke after hearing Christian, Jewish and Muslim prayers and musical interludes.

Abbas said: "We want peace for us and our neighbours."

The four leaders then symbolically shovelled soil for a newly-planted olive tree and held a closed-door meeting in a Vatican pavilion, following the collapse of US-backed Middle East peace talks earlier this year.

Francis called for the "courage" to make peace.

"Peacemaking calls for courage, much more so than warfare," said the Argentine pontiff, who invited the two during his visit to the Middle East last month.

Israeli-Palestinian negotiations, mediated by the US in July 2013 after a three-year-hiatus, have collapsed in late April 2014 after ‘Israel’ reneged on its promise to release Palestinian prisoners.

Al Ray contributed to this report.