PARIS--Bitter accusations against the Khmer Rouge dominated Cambodian peace talks yesterday, with Vietnam calling the communist group "the most barbarous regime ever known" and demanding it be destroyed like the Nazis.

Despite open antagonism at the international peace conference, some delegates expressed hope for progress in upcoming closed-door sessions.

Vietnamese Foreign Minister Nguyen Co Thach demanded the "perpetual eradication" of the Khmer Rouge.

Khmer Rouge leader Khieu Samphan charged in turn that Hanoi plans to "exterminate" the Cambodian people and nation and has no intention of withdrawing it troops from Cambodia next month as promised.

Diplomats from 20 countries joined in calling for a comprehensive peace plan, but none of their speeches Sunday and yesterday offered new proposals to end the nation's two decades of conflict.

Emerging as a seemingly irreconcilable difference was the future role of the Khmer Rouge, the strongest of three resistance groups fighting the Vietnamese and the pro-Hanoi government in Cambodia. The resistance is armed by China and led by Prince Norodom Sihanouk, a noncommunist who believes having the Khmer Rouge in Phnom Penh during an interim period leading to elections would be better than fighting them in the jungles.

Almost all delegates at the conference reviled the Khmer Rouge, which was routed in a Vietnamese invasion in early 1979 after its fighters killed hundreds of thousands of civilians in a revolution to reform the country into an agrarian commune.

"The genocidal Pol Pot regime is the most barbarous regime ever known in human history," Foreign Minister Nguyen Co Thach of Vietnam told the conference.

But China's Foreign Minister Qian Qichen cautioned that excluding any party from an interim government would be "dangerous."

"The reality in Cambodia today is the simultaneous presence of four political parties, each possessing its own armed forces," he said.

Qian called for the Vietnamese troop withdrawal under international supervision to be followed by a fourparty interim government headed by Sihanouk and including the Khmer Rouge.

Japan, the West and noncommunist Southeast Asian countries agree on that approach. Vietnam, the Soviet Union and Cambodia's pro-Hanoi government reject inclusion of the Khmer Rouge.

The conference now goes into closed-door committee sessions which may last several weeks before the foreign ministers return to Paris at the end of this month or early September. Three of four committees will focus on specific aspects of the complex peace process.

"The atmosphere in the conference room is one of optimism. There is a strong current toward a solution," Sihanouk told reporters.

On Sunday, Secretary of State James A. Baker III said, "We know the path to Cambodian internal reconciliation is likely to be long and arduous. But today we take the first steps."