A sharp deterioration in Egypt's relations with Israel is further complicating Washington's faltering efforts to move the Middle East peace process forward.

The U.S. has long relied on Egypt's key role as a mediator in the region, most crucially in trying to reconcile rival Palestinian factions. But those efforts are now stalled as U.S. Secretary of State Hillary Clinton rushes to Cairo to meet Egyptian President Hosni Mubarak on Wednesday — a clear sign of concern that Egyptian and Arab support for the Israeli-Palestinian peace efforts may be waning.

Clinton, who extended her Mideast trip by a day to come to Cairo, arrives at one of the lowest ebbs in three decades of Egyptian-Israeli peace. Over the past month, Egypt has been scaling back its already limited contacts with Israel in an apparent protest over Israel's refusal to halt Jewish settlement in the West Bank and east Jerusalem.

Egypt has tried to keep Israelis away from several international forums and censured an academic for meeting Israel's ambassador to Cairo. Egyptians have also bitterly blamed Israel for their culture minister's loss of the top post at the U.N. culture agency, UNESCO, and even for attempts by African countries to grab a bigger share of the Nile's waters.

"If generally they have been cool, now their ties seem to be frosty," said Samir Ghattas, head of the Cairo-based Maqdus Center for Strategic Studies.

Israel acknowledged the Egyptian frictions but tried to play them down, contending the hard line against the Jewish state comes more from the society than from Egypt's government.

Egypt was the first Arab country to make peace with Israel in 1979 and though ties have never been warm, it has played a critical role as Mideast peace mediator. The Egyptians helped end the Gaza war early this year. More recently, Egyptian and German mediators brokered a deal between Israel and Hamas to exchange 20 Palestinian women prisoners for the first video images of Israeli soldier Gilad Schalit since he was captured in a cross-border raid from Gaza in 2006.

The deterioration of relations poses another obstacle to the Obama administration's plan for Egypt and other Arab countries to forge a regional peace deal.

Other Arab countries — most of which refuse all contact with Israel — have rejected the U.S. call for small steps toward normalization with Israel that could create a better environment to restart Israeli-Palestinian peace talks.

Palestinians are demanding a total settlement freeze before they will return to talks, suspended since late last year.

Clinton angered Arabs this week when she lauded Israel for what she called an unprecedented offer to curb Jewish settlement on lands Palestinians hope to incorporate in a future state. It was unusually strong praise for Israeli peace efforts without explicitly mentioning any positive acts by the Palestinians.

Arab governments interpreted her comments in Jerusalem as a tilting of U.S. policy toward Israel. On Monday in Morocco, Clinton issued what she called a clarification, saying her words in Jerusalem were meant as "positive reinforcement" for the Israelis. She said Israel's effort still fell far short of U.S. expectations, and strongly praised the Palestinians.

Her decision to extend her Mideast trip with a hastily arranged visit to Cairo, where she arrived late Tuesday, appeared linked to Egyptian concerns about signs of a recalibration of the U.S. approach to the peace process.

And there are other signs the process is not moving in the direction Washington would like.

Last week, Bahrain's lower house of parliament approved legislation penalizing all contact with Israel. Around the same time in Jordan — the only other Arab country to have signed a treaty with Israel — a coalition of opposition parties and trade unions demanded a "cancellation" of the 1994 peace agreement, saying it has only benefited Israel.

Egyptian officials are reluctant to speak publicly about the tensions with Israel. But behind closed doors, they express frustration at Israel's continued settlement.

That frustration was expressed two weeks ago when Egypt rescinded an invitation for Israeli doctors to attend a breast cancer awareness conference in Cairo sponsored in part by U.S.-based Susan G. Komen for the Cure. The U.S. foundation said it launched a diplomatic campaign to reverse the decision and the Israelis eventually were invited, but chose to stay away.

Last week, Egypt pressed other Arab countries to block a key meeting for the Mediterranean Union, which includes Arab states, the European Union and Israel, because controversial Israeli Foreign Minister Avigdor Lieberman planned to attend the Paris forum.

"Egypt's line, which other countries followed, was not to be associated with Israel," said Israeli Foreign Ministry spokesman Yigal Palmor. "They politicized the whole thing in a very negative manner."

Another setback came when Hala Mustafa, a liberal-minded member of Egypt's ruling party and editor of the quarterly journal Democracy, was censured for meeting with Israel's ambassador to Egypt.

Senior Israeli officials also are visiting Egypt less frequently these days.

And experts saw another sign of the heightened tensions in Mubarak's speech to his ruling party this week. He made little mention of the stalled peace process, a topic that usually tops his foreign policy statements.

Instead, he talked about water supplies. In recent weeks, Egyptian state-owned papers have accused Israel of inciting African countries, who control the Nile River's water, to work against Egypt. These countries have been demanding a new Nile water sharing that will reduce Egypt's quota.

Egyptian Culture Minister Farouk Hosny's failure to win the top job at UNESCO recently further soured relations. He blamed "a group of the world's Jews" for the loss and also criticized Israel. Israel did not comment on the criticism.