Even by the volatile standards of Israeli politics, the comeback of Ehud Barak has been a remarkable one.

Ousted as prime minister in 2001 after the acrimonious failure of the Camp David peace talks, Mr Barak left the political stage for almost six years to pursue a career in business. Yet in June, Israel's most decorated soldier and former chief of staff was back, taking the helm of his centre-left Labour party and assuming the post of defence minister in the coalition government headed by Ehud Olmert.

Mr Barak's political revival passed yet another milestone on Saturday, when he joined the country's political grandees at the annual rally to mark the anniversary of Yitzhak Rabin's death. Facing a crowd of 100,000 mourners in Tel Aviv, Mr Barak made an emotional vow to defend the legacy of the slain politician. "We will do everything in our hands to reach the peace you dreamed of and fell for," he said.

Yet to his critics, Mr Barak's words rang hollow. They complain that the man who was once willing to go further than most to reach a deal with the Palestinians has been absent from the -latest drive to reach a -comprehensive peace settlement. His stance has reportedly sparked tensions not only within his own party but also with Mr Olmert, who is in the midst of preparing for a US-sponsored peace meeting in Annapolis, Maryland, this year.

Analysts and former aides to Mr Barak say his lukewarm support for peace efforts is explained by a complex mixture of the political and the psychological: they say the breakdown of his talks with Yassir Arafat, the Palestinian leader, at Camp David in 2000 has made him wary of making concessions to the Palestinians. His scepticism may also be fuelled by electoral considerations, with Mr Barak positioning himself as an uncompromising defender of Israeli security interests.

Yossi Beilin, the leader of the leftwing Meretz Yachad opposition party and a former minister under Mr Barak, has been at the forefront of the critics.

"It is very difficult for me to understand how he could put himself to the right of Olmert," he told the Financial Times. "I think this goes beyond the political. He took the failure of Camp David very personally and he is still trying to punish the Palestinians for not accepting his proposal at the time."

Haim Ramon, deputy prime minister and one of Mr Olmert's closest allies, told Israeli army radio this week: "Contrary to what we've seen so far, I hope that Barak will once again act to bolster the process. I would like to hear from the Labour chairman what he is doing to help the prime minister ahead of the Annapolis -conference."

Expectations regarding the Annapolis talks have been very low, with little evidence that the Israeli and Palestinian negotiators preparing the meeting are making real progress.

As defence minister, Mr Barak is in charge of upholding security and protecting Israeli settlements in the West Bank. Yet so far there has been no sign that he plans to use his powers to ease the lives of ordinary Palestinians, for example by lifting severe restrictions on travelling around and out of the territory.

The Hamas-controlled Gaza Strip seems even less likely to benefit from goodwill gestures ahead of the Annapolis meeting. Mr Barak has taken steps towards cutting fuel and power supplies to its 1.5m residents. He has also repeatedly raised the prospect of a "large-scale military operation" to root out Islamist militants and end the barrage of rockets fired from the territory.

Zvi Shtauber, a former foreign policy adviser to Mr Barak and now the director of Israel's Institute for National Security Studies, says: "He doesn't anticipate a breakthrough [at Annapolis] - don't forget that Ehud Barak was already there. He is less naive after Camp David.

"His tenure as defence minister is the vehicle to come back in the eyes of the Israeli public. Sooner or later there will be an election and he knows that Israel has been moving to the right."

Yet according to the latest polls, only 17-19 per cent of Israelis believe that Mr Barak would be the best leader for the country - down from previous polls and far behind Benjamin Netanyahu, leader of the rightwing Likud party.

Mr Barak's political comeback, it seems, still has some way to go.