TOKYO, JUNE 4 -- Peace talks aimed at ending Cambodia's 11-year war appeared to be collapsing today just as they were set to begin when the delegate of the Khmer Rouge guerrillas failed to attend because his group was not given equal representation.

Japanese officials who had hoped to arrange a cease-fire among the four warring Cambodian factions said they were working to keep the scheduled two-day meeting from breaking up. Foreign Ministry officials hinted that Thai and possibly Chinese officials were also seeking to prop up the talks.

Until now, talks in an international peace process that began two years ago have included on an equal basis all four Cambodian groups: the Vietnamese-backed government of Prime Minister Hun Sen and the three guerrilla factions joined in a U.N.-recognized coalition. The Communist Khmer Rouge is the largest and most powerful of the guerrilla groups.

But Japan, which is hosting international peace talks for the first time, gave in to Hun Sen's demands that the Khmer Rouge be excluded from signing any agreement, according to another Japanese official.

The Phnom Penh government has ruled out any future role in Cambodia for the Khmer Rouge, blamed for the deaths of more than 1 million Cambodians when it ruled Cambodia from 1975 to 1979.

In a statement, Khmer Rouge representative Khieu Samphan blamed Japan for the faltering of the talks, accusing it of failing to allow equal representation for the four Cambodian factions. "Khieu Samphan said in the statement he could not agree to such an arrangement and would therefore not attend," the Japanese official said.

Japanese Foreign Ministry sources said, however, that they had "made it clear" that the talks were to be between Hun Sen and Prince Norodom Sihanouk, nominal leader of the guerrilla coalition.

As Tokyo struggled to sustain the talks, fighting continued.

Khmer Rouge radio, monitored in Bangkok, said its guerrillas were closing in on Sre Umbell and Kompong Som, the two most important government-held ports, after overrunning two villages on Cambodia's southern coast. Western diplomats were unable to confirm the fighting but said the reports were timed as a propaganda boost.