World powers trying to revive peace talks between Israelis and Palestinians may be flogging a dead horse and their repeated failure is eroding what credibility they have left as mediators.

Some political analysts argue it is now time for them to scale back their ambitions. With faint hope of a deal, would-be peacemakers may inevitably find themselves seeking to manage rather than resolve the generations-old conflict.

The latest effort by the Middle East Quartet -- a body comprising the United States, the European Union, Russia and the United Nations -- was arguably a failure before it began.

Quartet representatives held separate meetings with the parties in Jerusalem Wednesday, falling short of their stated aim of bringing them to the same table for talks on how to resume direct negotiations on a permanent peace deal.

The mediators said the sides had agreed to make proposals on issues of territory and security within three months. But Palestinian and Israeli analysts saw little hope the latest push could succeed where years of direct talks have failed.

The Quartet is irrelevant because it is stuck on a road which is not leading anywhere, said Shlomo Avineri, a professor of political science at the Hebrew University of Jerusalem and a former director general of the Israeli Foreign Ministry.

I find it laughable, ridiculous, said George Giacaman, a Palestinian political scientist at Birzeit University in the West Bank. There have been 20 years of negotiations and they haven't arrived anywhere. It's a mantra they keep repeating.

They have to keep trying or someone will say the emperor is naked, he said. They have to keep moving to stay in the running, but I doubt they themselves believe they will be successful.

SETTLEMENT STANDOFF

Established a decade ago, the Quartet has in recent months taken a leading role in attempts to broker new talks. It has stepped into the fray following the failure of U.S. President Barack Obama's administration to resuscitate negotiations.

Unsurprisingly, Quartet envoy Tony Blair has run into the same set of problems that bedevilled Obama's efforts.

The immediate obstacle is the standoff over Israel's expansion of Jewish settlements on the land where the Palestinians aim to found an independent state. World powers view the settlement as illegal under international law.

While Israeli Prime Minister Benjamin Netanyahu says he wants talks now, the Palestinians say he must halt all settlement-building before they come to the table. That is something his government will not do.

The dispute points to the deeper problem: what some now see as an unbridgeable gap between the Palestinian quest for independence and an end to occupation, and Israel's attachment to land it deems of strategic and spiritual importance.

Even at the pinnacle of the peace process in 2000, Israelis and Palestinians were unable to agree terms for a permanent solution to their conflict through the creation of a Palestinian state next to Israel in the West Bank, the Gaza Strip and East Jerusalem -- territories Israel occupied in a 1967 war.

Today, mediators face a layer of added complications.

The list is long and includes the emergence of rival Palestinian administrations in the West Bank and Gaza, controlled since 2007 by Hamas, which is hostile to Israel.

In Israel, there has been a swing to the political right, a shift helped by the last Palestinian uprising. Add to that the fact that half a million Israelis have now settled in the would-be Palestine, and hopes for a deal seem far fetched.

I don't think the conflict is resolvable in the foreseeable future, said Moty Cristal, a negotiator who served four Israeli prime ministers between 1994 and 2001. This is something that Israelis and Palestinians cannot do at the moment ... at it's current stage, the maximum it could be is manageable.

EGYPTIAN MEDIATION

The Quartet's failure stands in stark contrast to Egypt's recent success in brokering a prisoner swap between Israel and Hamas, which exchanged an Israeli soldier captured by gunmen in 2006 for 1,027 Palestinian prisoners.

The deal disheartened Palestinian leaders in the West Bank who, unlike Hamas, oppose armed conflict with Israel and believe peace talks are the way to end the conflict.

President Mahmoud Abbas' strategy of negotiating with a far stronger adversary has always hinged on an assumption that world powers would not simply mediate talks, but also put pressure on Israel to give ground.

For the Palestinians, the Quartet's inability to secure a full settlement freeze has come to symbolise its impotence. They mainly blame the failure on the United States, Israel's closest ally and seen as the only power truly able to influence it.

A settlement freeze was a requirement of a 2003 peace plan, drawn up by the Quartet and known as the road map for peace.

If the Quartet is going to play any credible role, it must really be able to enforce the terms of reference, and the compliance with these terms of reference, particularly those that have led to an agreed text, like the road map, said Nabil Shaath, a veteran Palestinian official.

That frustration gave rise to the Palestinians' bid for full membership of the United Nations, an initiative they hope will engage more countries in the search for a peace deal. The United States and Israel firmly oppose the unilateral move.

The Quartet's position, as outlined in a September 23 statement, reflects the U.S. view that bilateral talks must resume between the sides, reiterating its commitment to seeking a comprehensive resolution as its aim.

For now, Avineri said mediators should shift their focus.

The Quartet is basically wrong-headed because it is avoiding realisation that the attempt to bring the two sides together to negotiation about a final status agreement is wrong. It hasn't worked now for a long time, he said.

(Writing by Tom Perry)