The Saudi king chastised Arab leaders for infighting and said their divisions have fueled turmoil around the Mideast, prodding them to take united action at a summit Wednesday aimed at reviving a peace offer to Israel.

The gathering is to revive a 2002 initiative offering Israel peace with the Arab world if it withdraws from lands it seized in the 1967 Mideast war — a proposal the United States and Europe hope can bolster efforts to resume the stalled peace process.

Arab leaders have refused calls for changes in the plan to win Israeli acceptance, but U.S. allies Egypt, Saudi Arabia and Jordan want the summit participants to give them flexibility in promoting the offer to Israel and the West.

Saudi King Abdullah opened the summit with a strongly worded speech, painting a bleak picture of the crises and bloodshed in the region — Lebanon, Iraq and Sudan — and lecturing the leaders that it was time to act.

"The real blame should be directed at us, the leaders of the Arab nation," he said. "Our constant disagreements and rejection of unity have made the Arab nation lose confidence in our sincerity and lose hope."

He pointed to the bloodshed in Iraq, where he called the U.S. military presence an "illegitimate occupation" and warned that "abhorrent sectarianism threatens a civil war." He also called for the lifting of the "oppressive" international financial embargo on the Palestinians "as soon as possible so the peace process will get to move in an atmosphere without oppression."

Washington's Arab allies are increasingly worried that the region's crises are building up to a point of disaster, with fears of disintegration in Iraq, increasing Iranian power in Iraq and Lebanon, and growing militancy fueled by the Palestinian-Israeli conflict.

Saudi Arabia has taken a leading role in trying to mediate an easing of the tensions, particularly in the peace process. The kingdom brokered the formation of a Palestinian unity government between the moderate Fatah party and the militant Hamas group, hoping it would be able to enter peace talks with Israel and prompt the West to end the financial embargo on the previous Hamas-led administration.

Israel, which rejected the Arab peace initiative in 2002, now says it could accept it if it is amended, particularly to water down provisions calling for a "just solution" to the issue of Palestinian refugees.

Secretary of State Condoleezza Rice and U.N. Secretary-General Ban Ki-moon both toured the region ahead of the summit, trying to build momentum for the peace process and the Arab initiative. Ban spoke at the summit, calling the initiative "one of the pillars of the peace process" and urging Israel to "take a fresh look at it."

Arab League Secretary-General Amr Moussa rejected amending the peace offer, saying, "They tell us to amend it, but we tell them to accept it first, then we can sit down at the negotiating table." But he said the Arabs must "do more to convince" the Israelis on the offer.

The summit is to relaunch the peace plan as is, but it will create "working groups" to promote the offer in talks with the U.S., U.N. and Europe — and perhaps Israel. The summit's final resolution calls on Israel to accept the initiative and "seize this opportunity to resume serious, direct negotiations on all tracks."

Saudi Arabia, Jordan and Egypt hope the working groups can negotiate behind the scenes to make the initiative more palatable to Israel and the West and the basis for restarting talks. Jordanian Foreign Minister Abdul-Ilah al-Khatib told the Arab daily Al-Hayat there was a "potential" that the working groups could hold direct talks with Israel.

Much depends on the makeup of the working groups, which could be the source of dispute at the summit. Some have spoken of restricting the membership to Saudi Arabia, Jordan, Egypt and the United Arab Emirates. But the more hardline Syria — which opposed changing the initiative — may also seek to join, fearing it will be sidelined by the moderates.

EU foreign policy chief Javier Solana, a guest at the Riyadh summit, said both sides should show flexibility. "The important thing is to get the negotiations started. In any negotiations there are changes in positions, because negotiations are like that," he said.