VIETNAMESE FORCE HELPING CAMBODIA, DIPLOMATS ASSERT

By STEVEN ERLANGER, Special to The New York Times
Published: February 23, 1990

Several thousand Vietnamese troops and military advisers returned to Cambodia last fall after a much-publicized withdrawal and are helping the Cambodian Government to defend two strategic cities from guerrilla attack, two senior Eastern European diplomats say.

The diplomats said the Government invited Vietnamese forces back in October, a month after it announced their departure. The report indicates the precarious position of Cambodia's Vietnamese-installed Government, which is under attack from the guerrillas of the Khmer Rouge and other Cambodian forces opposed to the Vietnamese influence.

Cambodian and Vietnamese officials deny that there are Vietnamese troops in Cambodia or that any returned after their withdrawal. China, the Khmer Rouge and the two non-Communist Cambodian factions allied to the Khmer Rouge have asserted that thousands of Vienamese troops never left.

Defensive Lines in Northwest

But the Vietnamese Ambassador here, Ngo Dien, said in an interview that Vietnamese military advisers, whose numbers he did not disclose, had returned to Cambodia at Phnom Penh's request to help design strategic defensive lines in the northwest, fix tanks, trucks and armored cars and train officers and recruits in tactics and artillery.

If Phnom Penh risked its international credibility by secretly inviting Vietnamese forces back, it clearly felt that the loss of additional territory to the Cambodian insurgents would create unacceptable morale and political problems.

''On secret military matters, if the Cambodians need some people to advise or do something on a technical matter, we don't say no,'' Mr. Dien said.

Start of Rainy Season

The two Eastern European diplomats said all Vietnamese troops left Cambodia at the end of September, as Hanoi promised. But in response to an urgent request from Prime Minister Hun Sen after opposition advances and the fall of the gem-mining town of Pailin on Oct. 24, they said, Vietnam agreed to send a special force as large as 3,000 to help defend the perimeter of Battambang, Cambodia's second-largest city. The Vietnamese began to arrive by helicopter on Oct. 29, one of the diplomats said.

At least 5,000 Vietnamese troops are encamped around Battambang and Sisophon to insure that these provincial capitals do not fall to the Khmer Rouge and its allied non-Communist factions, the two Eastern European diplomats said.

One diplomat said Mr. Hun Sen was told by Foreign Minister Nguyen Co Thach of Vietnam at the end of December that Vietnamese troops would be withdrawn irrevocably at the start of the rainy season, around the end of April.

A third senior Eastern European diplomat said he had been told that at least 1,000 members of Vietnamese special forces entered Cambodia at the end of October, but he said he did not know if they were still here. ''I know Vietnam wanted to be clean before Jakarta,'' he said, referring to the conference in Indonesia that is scheduled to begin later this month to discuss the future of Cambodia. ''By now they might be gone.''

Little Fighting Believed

He said that to his knowledge they had done little fighting. ''But the important thing is that the Khmer Rouge knew that between them and Battambang, there were Vietnamese,'' he said.

The diplomat said it was difficult ''to draw a frontier between military advisers and soldiers,'' but added that now ''the presence of every Vietnamese adviser, specialist or even combatant is paid for by Cambodia.''

Asked why he would disclose such sensitive and embarrassing information, a senior Eastern European diplomat with long experience here said, ''I believe in the truth, and with changes at home, it is easier to tell it.''

Another Eastern European diplomat said Chinese, American and Southeast Asian aid was continuing to go to the opposition, ''and it is no shame for Vietnam to respond to a request for help.''

Denies Troop Involvement

Dith Munty, Cambodia's First Deputy Foreign Minister, said in an interview that there were no Vietnamese troops or military advisers here. Advised of Mr. Dien's comments, he then said that ''as far as I know, there are Vietnamese military attaches and aides working in Cambodia,'' but no troops.

He said statements that Vietnamese troops came to help in Battambang were not true and ''a fabrication.'' He said Cambodia welcomed international verification to prove that no Vietnamese troops remained.

Chum Bun Rong, a Cambodian Foreign Ministry spokesman, also said there were no Vietnamese troops here. ''If we had them, the Khmer Rouge could not seize a part of the country,'' he said. ''We welcome verification by an international team even before a peace settlement. We don't want to be hostage to accusations that poison the soil.''

Diplomats and aid workers say the Khmer Rouge control large areas of the countryside in a part circle beginning about 30 miles from the two city centers, where the three lines of defensive perimeters end. The Khmer Rouge have cut the Phnom Penh-Battambang rail line north of Pursat by blowing up two bridges, though Cambodian officials say they are under repair. #12,000 Living on Streets While the Khmer Rouge maintained they began a frontal attack on Battambang on Jan. 5 and set the city alight, in fact the attacks were mostly made with rockets. Troops did not penetrate the city's suburbs.

Foreign journalists were not allowed to visit Battambang until Jan. 23 and found the city quiet. But they flew into the city on a special flight and were not allowed to travel around the city, except to drive north to Sisophon and Poipet, within the defensive perimeters.

Aid workers and diplomats say that about 12,000 Cambodians displaced by the fighting are now living on the streets of Battambang and that 30 people a day reach the city hospital with gunshot wounds.

The Vietnamese withdrawal last September followed a nearly 11-year occupation that began with their expulsion in January 1979 of the Khmer Rouge Government, under which more than a million Cambodians died. Before the withdrawal in September, Vietnamese generals said they feared that Sisophon and Battambang might fall.

On Right to Seek Assistance

If those cities are taken, Cambodian officials privately say they fear a collapse of already low army morale and a panic in Phnom Penh.

Early last April, when Vietnam, Cambodia and Laos jointly announced that Vietnamese troops would leave Cambodia at the end of September, the declaration included a clause reserving to Cambodia the right to call on assistance again if needed.

Vietnamese officials said in September that should such a request come, it would be judged at the time. They said Hanoi had no interest in returning troops to Cambodia but wished to concentrate on building relations with the West, the United States in particular, which had made Vietnam's withdrawal a condition of diplomatic and commercial relations.

But the United States said that the unilateral Vietnamese withdrawal was not sufficient, and that normalization could only come after a comprehensive settlement in Cambodia. An American embargo on aid and trade to Vietnam continues, and Washington has blocked loans to Vietnam from the World Bank, the International Monetary Fund and the Asian Development Bank.

Shocked by Pailin's Fall

The Eastern European diplomats said Mr. Hun Sen's Government had been shocked by the fall of Pailin. In Hanoi, Maj. Gen. Tran Cong Man confirmed in an interview that Cambodian forces abandoned Pailin ''with no real reason'' when they thought Khmer Rouge forces were about to surround them.

''If a Vietnamese general had behaved like that, he would have been sentenced to death,'' General Man said. He also confirmed that Cambodian soldiers left the town of Svay Chek in northwest Cambodia to the Khmer People's National Liberation Front, after successfully defending it for weeks, when a shell happened to hit their commander's tent. When the Cambodian soldiers saw their commander being evacuated on a stretcher, they followed his litter out of town, General Man said.

A Khmer Rouge attack on Battambang at the end of September had worried ''the military lobby'' in the Phnom Penh Politburo, one Eastern European diplomat said. In early October two members, Deputy Defense Minister Pol Saroeun and the former Defense Minister and Deputy Prime Minister, Phou Thang, asked Mr. Hun Sen to invite some Vietnamese troops back. He refused several times. But on Oct. 26, after the panicky retreat from Pailin two days earlier, the diplomat said, Mr. Hun Sen spoke with Defense Minister Le Duc Anh and asked for the return of several thousand troops.

Mr. Anh was furious, the diplomat said.

But after two days of consultations in Hanoi, the diplomat said, Mr. Anh told Mr. Hun Sen that the Vietnamese would send 3,000 special forces, elite career soldiers who had not served in Cambodia, to help protect Battambang, but that they would be placed far from the city center. They were said to have begun arriving the next day, Oct. 29.

In Hanoi, General Man also denied that Vietnamese fighting troops were in Cambodia, but said that the Cambodian Army suffered from poor morale and weak leadership.