The Quartet on the Middle East failed to agree on a statement outlining the next step for the already fragile peace process.

Despite hours of discussions in Washington on Monday, by the end of the day they could not offer a unified position.

The mediators, from the UK, US, Russia and the EU, admitted that there was "more work" to be done before negotiations could resume.

A spokesman for the Obama administration said: "There is a time and a place for public statements and there is a time and a place for private diplomacy.

"We need to do more work, privately, quietly, with the parties, in order to see if we can't close these gaps."

The parents of captured soldier Gilad Shalit wrote to the Quartet as it met calling for more efforts to secure his freedom. The Shalits said their son's captivity was "one of the more pressing unsolved issues between Israel and the Palestinians".