U.S. Secretary of State Condoleezza Rice this weekend makes her fourth visit to Israel and the Palestinian territories since the November Annapolis peace conference with little to show for the U.S. effort.

Traveling ahead of President George W. Bush's May 13-18 trip to Israel, Saudi Arabia and Egypt, Rice left Washington on Thursday and will see officials on both sides - including in three-way sessions - to assess a peace negotiation with no visible sign of progress.

U.S. officials and analysts played down expectations for her trip, which begins in London for meetings on Friday to discuss reviving the Palestinian economy, reining in Iran's nuclear program and supporting newly independent Kosovo.

She is then expected to travel to Jerusalem and the West Bank to meet Prime Minister Ehud Olmert, Palestinian President Mahmoud Abbas and their top aides on Saturday and Sunday.

"It is all behind the scenes stuff. She is not going to say much in public. She really is trying to get the two sides to deal with, and make progress on, the core political issues," said a senior U.S. official who asked not to be named.

Among other things, the official said Rice would gauge "how active she needs to be in presenting her own ideas to each side in order to move the process forward."

The Bush administration has so far been loathe to float its own proposals to help the two sides bridge their differences, preferring to leave them to work these out directly.

Martin Indyk, a former U.S. ambassador to Israel now at the Brookings Institution think tank, was skeptical that the Bush administration was on the verge of offering its own ideas on how to craft a peace agreement to end the six-decade conflict.

"I see no indication of that. I think that their very clear attitude to this - at least the president's view of it - is that it's up to the parties to make the deal," Indyk said.

He said bilateral talks about borders, Jewish settlements, the status of Jerusalem and the fate of Palestinian refugees could be making headway but that Abbas' dissatisfied air after meeting Bush in Washington last week suggested otherwise.

"Abu Mazen [Abbas] left here in a very sour mood - and I think that is an indicator that things aren't going great," he said.

Indyk also said he found it "much more disturbing" that there has been little movement on the ground, saying Israel has repeatedly moved to expand settlements since the Annapolis, Maryland, peace talks and done little to remove significant roadblocks on the West Bank.

On the Palestinian side, it is unclear how much security forces under Abbas have been built up to take on militants.

In London, Rice will attend a meeting of the quartet of Middle East peace mediators comprising the European Union, Russia, the United Nations and the United States as well as a gathering of Palestinian donors.

She will also take part in a meeting of major powers - Britain, China, France, Russia, the United States and Germany - to discuss whether to improve a package of incentives offered to Iran in 2006 to suspend uranium enrichment.

The United Nations Security Council has imposed three rounds of sanctions on Iran for defying council demands that it suspend its uranium enrichment program, which could be used to make fuel for power plants or atomic weapons.

Iran has refused to buckle to the sanctions and has spurned previous offers of economic benefits to suspend its uranium enrichment, which it says is to make fuel for electrical power plants so it can export more of its valuable oil and gas.

In June 2006, the six nations held out incentives to Iran, including civil nuclear cooperation and wider trade in civil aircraft, high technology and agriculture, if Tehran suspended uranium enrichment and negotiated with the six.

Russia and China have argued for sweetening the incentives while the United States, which broke diplomatic relations with Iran after its 1979 Islamic revolution, has resisted.

One Western diplomat said he thought it was unlikely that the so-called P5+1 ministers would reach an agreement on sweetening the incentives offer, saying "I don't see any big breakthroughs here."

But another Western diplomat who asked not to be named said it depended on whether Russia and China - which favor a much sweeter incentives package - might be willing to accept a more modest improvement.

"This is really an exercise that is more, in our opinion, to stress again to the Iranian authorities and the Iranian public opinion, if possible, that there is this second part of the package that sometimes seems to have been forgotten," he said, referring to the incentives.