Israeli FM Tzipi Livni, Israeli PM Ehud Olmert, Palestinian president Mahmud Abbas and former Palestinian PM Ahmed Qorei (File)

Palestinian President Mahmoud Abbas says the Mideast peace conference called by the United States is a historic opportunity to resolve the Arab conflict with Israel.

He was speaking Sunday to tens of thousands of supporters in the West Bank city of Ramallah, at a rally marking the third anniversary of the death of Palestinian leader Yasser Arafat.

Hours after Mr. Abbas' speech, Palestinian negotiators were stopped at an Israeli checkpoint as they drove to Jerusalem for talks with Israeli officials about the U.S.-hosted conference, which could begin later this month.

To protest the Palestinians' treatment, their chief negotiator, Ahmed Qureia canceled Sunday's meeting and asked Israeli officials to move the talks abroad. An Israeli spokesman says Israel regrets the incident and will investigate it.

No specific date has been set for the Mideast peace conference, although U.S. officials are aiming to begin talks before the end of this year. The conference will take place in the city of Annapolis, Maryland, about 60 kilometers east of Washington.

In his Ramallah speech, Mr. Abbas said his government will have no dialogue with the Hamas militant group until it reverses what he called its "black coup" in the Gaza Strip. Hamas seized the territory in June in fighting with Mr. Abbas' Fatah movement.

Fatah supporters held several rallies in Gaza Sunday in honor of Arafat, including a gathering of about 10,000 people in the central Gaza refugee camp, Bureij. At one rally, Hamas security forces opened fire at Fatah activists and wounded several people.

Some information for this report was provided by AFP, AP and Reuters.