Cambodian and U.N. negotiators reached tentative agreement today to create a tribunal to try former Khmer Rouge leaders for genocide, raising hopes for justice among Cambodians a quarter-century after the communist movement killed an estimated 1.7 million people.

The draft accord, signed after five years of difficult negotiations, would set up a body in which foreigners and Cambodians would serve as judges and attorneys. The accord allows the prosecution of senior Khmer Rouge leaders and those "most responsible" for human rights violations, but did not name any suspects.

Vann Nath, one of eight remaining survivors of the Tuol Sleng prison and torture center operated by the Khmer Rouge, welcomed the agreement. "It is not only I who need to see a trial, but all the victims, all the people of Cambodia," said Vann Nath, a painter whose works testify to Tuol Sleng's atrocities in excruciating detail.

Surviving senior Khmer Rouge officials include Nuon Chea, the regime's number two man, Khieu Samphan, who was head of state, and Ieng Sary, a former deputy prime minister. Ieng Sary, convicted in 1979 by a Cambodian court in absentia of genocide, was pardoned seven years ago by King Norodom Sihanouk and now lives in a villa in Phnom Penh, the capital.

The draft agreement goes to the U.N. General Assembly and the Cambodian National Assembly for approval.

"If the General Assembly approves this agreement and if it is ratified by the competent authorities of Cambodia, this is only the beginning," Hans Corell, the lead U.N. negotiator, said at a news conference in Phnom Penh.

During its rule, from 1975 to 1979, the Khmer Rouge carried out mass executions in an effort to impose agrarian communism on Cambodia. Large numbers of people also died of disease and starvation during that period.

A year ago, many analysts were saying that justice would sidestep Cambodia's 12 million people, more than a third of whom lived through the Khmer Rouge years. The Cambodian legal system is highly politicized, human rights workers say, and cannot be counted on to deal with the issue.

The United Nations began negotiating with Cambodia in the late 1990s, but in February 2002, Secretary General Kofi Annan cut off talks, saying he did not believe Cambodia was committed to ensuring international standards of justice. Under international pressure, the U.N. General Assembly unanimously passed a resolution in December requiring Annan to return to the table.

Corell said the tribunal would act in accordance with international standards of justice. The agreement specifically refers to the International Covenant on Civil and Political Rights, which Cambodia has ratified, he said.

"These articles are designed to ensure a fair and public trial by an independent and impartial court," he said.

But human rights groups say that great hurdles lie ahead for a tribunal that, unlike fully international courts for war crimes committed in Rwanda or the former Yugoslavia, will include both Cambodian and international judges and prosecutors.

The Cambodian legal system is not yet able to conduct trials by international standards, said Demelza Stubbings, director of the Asia Pacific program at Amnesty International in London. "It's weak," she said. "It's politicized. It's been subject to corruption and political interference for years."

She added, "It's very difficult to see how it will be able to turn around from that to meet the enormous task placed in front of it."

The agreement envisions a trial court with appeals directly to the country's Supreme Court. Convictions could result in a maximum penalty of life in prison.

Special correspondent Molly Ball in Phnom Penh contributed to this report.