BANGKOK, Thailand--Diplomatic efforts began Wednesday in Bangkok, Beijing and Paris to try to resolve the 11-year-old Cambodian war, following reports of guerrilla attacks in Phnom Penh and Cambodia's second-largest city.

Khmer Rouge guerrillas claimed they attacked the Cambodian capital with grenades Saturday night, forcing the premier and president to flee toward Vietnam. But the claim could not be confirmed, and previous communist Khmer Rouge claims have been exaggerated.

The non-communist resistance forces of Prince Norodom Sihanouk, allies of the Khmer Rouge, said they launched a series of grenade attacks on Phnom Penh between Dec. 5 and 10, wounding 16 Vietnamese and two Cambodian policemen.

The Cambodian government's SPK news agency on Tuesday did not mention any attack.

Igor Rogachev, a Soviet deputy foreign minister, arrived in Beijing on Tuesday for talks on Cambodia with Chinese Foreign Ministry officials. The governments are discussing an Australian proposal calling for the Vietnam-backed government in Phnom Penh to be replaced by an interim U.N. administration until free elections can be held, said Soviet Embassy spokesperson Yuri Lysenko.

The Soviets back the pro-Vietnamese government, while China arms the guerrillas.

The French Foreign Ministry yesterday scheduled a meeting in Paris on Jan. 15-16 for the five permanent members of the U.N. Security Council to discuss Cambodia, and the Australian plan could be on the agenda.

The meeting "will permit an examination of all the proposals advanced in recent weeks concerning Cambodia and a study of all means that might bring an end to armed conflicts on the ground," the ministry said. "It comes at a time when it appears possible to envisage an increased role for the United Nations in the settlement process."

The Australian plan would require backing from all five permanent members of the Security Council: the U.S., USSR, China, Britain and France.

Indonesia's foreign minister, Ali Alatas, arrived in Thailand yesterday in hopes of meeting representatives of Cambodia's Vietnamese-installed government and the three guerrilla groups to hear their views on the Australian plan and on efforts. Indonesia has been the host of several regional peace conferences.

A Thai military intelligence officer, speaking on condition of anonymity, said yesterday that "The Khmer Rouge are clearly...moving deeper and deeper. They want to sabotage the credibility of the government."

The Khmer Rouge said earlier they had attacked and set ablaze the second-largest city, Battambang, on Friday and Saturday. A Western diplomat in Thailand confirmed that Battambang was attacked but said "the effect was more psychological than strategic."

The reported attack in Phnom Penh, if confirmed, would be the most serious in the civil war.

The Khmer Rouge broadcast said resistance forces lobbed five grenades Saturday into the center of Phnom Penh near the office of the Central Committee of the Communist Party, killing or wounding some Vietnamese and "lackey puppets."

Another broadcast said the guerrillas attacked the city and suburbs with 32 grenades and plastic explosives, killing or wounding some Vietnamese soldiers and others who were drinking near ahotel. Vietnamese secret agents and Cambodianpolicemen were killed in the suburbs, thebroadcast said.

The Cambodian government's SPK news agency,monitored in Bangkok, did not mention any attack.SPK said Sunday's National Day celebrations tookplace in "total security" and that Saturday andMonday also were peaceful.

The guerrillas said their attacks preventedPremier Hun Sen from meeting in Phnom Penh withAustralian Deputy Foreign Secretary MichaelCostello for talks on a peace plan. They said HunSen went from Ho Chi Minh City to Cambodia'seastern Svay Rieng province, bordering Vietnam, tomeet the envoy