The Phnom Penh government categorically denied today that it had given permission to two United Nations agencies to open offices in Phnom Penh or to launch a massive emergency relief operation to stave off a famine in Cambodia.

In a Phnom Penh broadcast monitored in Bangkok, the official SPK news agency quoted a foreign ministry spokesman who said aid would be accepted only if relief organizations agreed to three conditions including a promise not to help Pol Pot's side in that country's civil war.

Last week the United Nations Childrens Fund and the international Committee of the Red Cross announced they had been given the go-ahead to mount a large-scale aid project to distribute $100 million worth of food and medicine to Cambodians and to oversee this observation from within the country.

Now, according to the broadcast, these two organizations must accept conditions contrary to their charters if they are to proceed with the desperately needed relief program.

A U.N. spokesman here said tonight that since the relief agencies had not been officially contacted by the Phnom Penh government they would continue to plan the relief projects.

But this broadcast was only part of a new campaign by Phnom Penh and Vietnam to insure that no aid reaches civilians living in Pol Pot sanctuaries even if this means the loss of all aid to Cambodia. Yesterday Vietnamese officials denied that there was even a famine in Cambodia.

"There is a food shortage, yes, but not this so-called famine that the West is playing up," said Cu Dinh Ba, counsellor with the Vietnamese mission at the United Nations. "This so-called famine is a trap to try to supply food and ammunition to the Pol Pot guerrilla forces."

Moreover, the Vietnamese said the military campaign by ousted premier Pol Pot poses a greater threat to Cambodia than the food problem.

Currently the Vietnamese Army and troops of the Vietnamese-backed Heng Samrin government in Phnom Penh are trying to wipe out the remaining Pol Pot forces inside Cambodia. The new Vietnamese statements, made in an interview yesterday, appear to be aimed at preventing assistance to civilians in Pol Pot's area of Cambodia even if that means the possible loss of all aid to Phnom Penh.

Since Heng Samrin's government is not recognized by the United Nations, the Vietnamese are the major source of information here from that country.

The Vietnamese also revealed yesterday that the Heng Samrin government privately sent a letter to the United Nations secretariat stating that any relief efforts to Pol Pot's forces would be considered interference in the internal affairs of Cambodia and would not be tolerated. That statement had been broadcast Friday on radio Phnom Penh.

In recent months Western aid experts and journalists have visited Phnom Penh and described Cambodia as a "country about to die." Eyewitness accounts from aid officials who have set up offices in Phnom Penh for an estimated $100 million emergency relief campaign contend that the country faces famine and epidemics of a scale approaching the disaster of Biafra.

"Saying there is only a food shortage in Cambodia is like calling Dachau [the Nazi concentration camp] a reeducation camp," said an expert involved in the international relief effort.

Yet despite the uniform descriptions of the misery in Cambodia, both Ba and Vietnamese ambassador Ha Van Lau yesterday argued in an interview that these reports were grossly exaggerated. They use words like "Chinese plot" to describe international aid organization efforts to provide food and energy to both sides of the Cambodian civil war.

"The main concern of the people in Cambodia is not the food problem," Ba said. "With one good harvest they can solve the food problem and there are no epidemics in Cambodia. The main concern is the return of Pol Pot."

Ba said, however, that he did not know how much rice currently has been planted.