China indicated today that its officials in Cambodia had moved into the countryside and would continue to support a guerrilla war against Vietnamese-backed insurgents who reportedly have taken the capital of Phnom Penh.

A reliable Chinese source said China's embassy was "still in Cambodia," but indicated that it was no longer in Phnom Penh.

"This is just the beginning, not the end, of the fihgt," he said.

Vice Premier Teng Hsiao-ping, in a benquet speech honoring former Cambodian head of state Norodom Sihanouk, did not say specifically what kind of support would be given China's badly beaten Cambodian allies, however. It appeared that Peking might shift its major resources to its own border with Vietnam.

Although reliable reports of the capture of Phnom Penh did not come until shortly after Teng's address, Peking had already begun efforts to evacuate its citizens from the Cambodian capital. Teng seemed aware that Phnom Penh's fall was near as he called on Cambodians to continue a "people's war" against "vietnamese aggression."

People's war is a concept that Cambodian leaders like Pol Pot have used with in creasing frequency as their military position has deteriorated. It refers to the late chairman Mao Tsetung's theory of guerrilla war conducted with the aid of peasants from bases in the countryside against better-armed forces based in cities.

"We are sure that, under the leadership of the Communist Party of Kampuchea [Cambodia], the Kampuchean Army men and people who have been tempered in protracted war will defeat the aggressor through sustained struggle and a people's war and win the final victory of their war of selfdefense," Teng said.

Sihanouk echoed the theme in is speech at the banquet, according to the New China News Agency: "We people of Kampuchea are waging a protracted people's war to defend our territory. We will rely on our own efforts and we are fully confident that our just cause will be victorious."

Ciplomatic sources here said the staff of the other remaining foreign legations in Phnom Penh, principally the Yugoslavs and the North Koreans, had been taken by truck to an airstrip about 30 miles outside Phnom Penh and then flown to Bangkok.

The Chinese supplied the Cambodian Communists with a rear base just inside southern China in the 1960s and 1970s and could do the same for the several Cambodian leaders, including Premier Pol Pot and President Khieu Samphan, who have reportedly fled Phom Penh.

Teng's outspoken praise of Sihanouk -- contrasted to his single, formal salute to other individual Cambodian Communist leaders -- suggested, however, that Peking might be considering anointing the former monarch as the leading Cambodian ruler in exile, a role Sihanouk played when he lived in Peking from 1971 to 1975.

Sihanouk himself, however, expressed his loyalty to Pol Pot in his banquet speech.

"We Kampuchean people are strongly united under the leadership of the Kampuchean Communist Party and its leader his excellency Secretary Pol Pot, and are filled with hatred for the Vietnamese aggressors and their masters.

Teng gave no hint last night that Sihanouk had changed his plans to fly to the United Nations and demand that the Security Council take some action against Vietnam. The former Cambodian monarch arrived here on a Chinese civilian aircraft last night after spending three years as a virtual prisoner of the Cambodian leaders he is now scheduled to defend in the Security Council debate.

China's principal goal in supporting the Cambodian government was to limit the expansion of influence in Southeast Asia by Vietnam, which is now closely allied with China's archfoe, the Soviet Union. The apparent Vietnamese victory in Cambodia appears to shift the focus of the Sino-Vietnamese conflict back to their common border, where a number of violent incidents have taken place in recent months.

Chinese officials said they had no information on reports from Bangkok sources that several top Cambodian leaders including Deputy Premier Ieng Sary, Pol Pot and Khieu Samphan, had boarded a flight to Peking this morning.

Diplomatci sources here said foreign residents of Phnom Penh were being evacuated by truck to the town of Battambang on Thailand's border. The same sources said they were told the retreating Pol Pot government was attempting to evacuate its civilian supporters from the east to western sanctuaries, although some diplomats doubted such efforts could succeed.

Teng called Sihanouk and former premier Penn Nouth "respected old friends of the Chinese people," and added: "Out meeting greatly warms our hearts."

The Chinese have cut all aid and all rail links to Vietnam. The chinese ambassador to Peking is currently in Vietnam on home leave, officials here said.

In perhaps its most pessimistic report on the border situation in several weeks, the official New China News Agency said yesterday that "while continuously creating provocative and bloody indidents along the Sino-Vietnamese border, the Vietnamese authorities are expelling inhabitants in the Vietnamese frontier areas into China to further 'clear up' these areas in preparation for war against China."

U.S. government sources have reported that substantial numbers of Chinese soldiers have moved to areas bordering Vietnam in the last several days. They are dquipped with tanks, trucks, heavy artillery, Mig19 fighter planes and IL28 bombers.