The recent defection of a once-powerful Vietnamese leader is part of a final housecleaning operation to remove the last China sympathizers but does not reflect a serious rift in the government on other issues, according to diplomatic sources here.

"They are working through the system, weeding out all of the people with Chinese sympathies," one source said. "I think they are simply tidying up."

Rumors of a deep split in the government ranks spread after the recent defection to China or Hoang Van Hoan, an early Communist leader who helped Ho Chi Minh set up the Indochinese Communist Party a half century ago.

In addition, diplomatic sources said that at least two other former leaders are under house arrest because of their past ties to China.

They said the cleanup is still going on at the lowest levels and that anyone suspected of Chinese sympathies is being demoted or moved out.

However, they said accounts of a serious disagreement and possible purge that might shatter the leadership are exaggerated.

The defection of Hoan, 74, last month has been an embarrassment to Vietnamese leaders, who minimize its significance.

Nguyen Co Thach, secretary of state for foreign affairs, acknowledged the defection in a new conference with foreign reporters. But he stressed that Hoan had not been a member of the Politburo for three years. "He had been out of the leadership since 1976," Thach said.

Thach also denied that any of the other former leaders believed purged are under house arrest. Asked if they are free to move about Hanoi, Thach said, "Why not? Why not?"

Vietnam's Communist Party had been considered one of the world's most unified and there have been few reports of internal disagreements that are common in other Communist countries.

The split developed when Vietnam fell away from China's influence and grew wider last summer when the Chinese cut off sizable aid to the Vietnamese. Thousands of ethnic Chinese, some of whose families lived in this country for generations, left Hanoi.

The diplomatic sources said most of the Chinese left before the Chinese invasion last February. They said that only about 10,000 ethnic Chinese remain out of the 100,000 who once lived here.

"The government set a date for them to leave," a source said. "They were told they either had to get out or that they would go to the "new economic zones.""

These zones were set up originally to mobilize a large number of urban dwellers for farm work in the countryside. Most are located in remote areas where farming is difficult, and many of the recent Vietnamese refugees have said they feared they would starve to death if sent to live on them.

Hoan defected in July at Karachi, Pakistan, where he feigned illness and stepped off a plane bound for East Berlin, according to an account published in the Far Eastern Economic Review.

Sources here said he had been under heavy pressure from former allies because he had hardly bothered to cover up his admiration for China, where he had served as ambassador.

Last April, he was required to appear at an exhibition celebrating what the Vietnamese regard as their victory over Chinese forces. He is reported to have decided to defect soon afterward.

"He felt he had to get out before something serious happened to him," said one member of the diplomatic community.

The sources identified the two others believed to be under house arrest as Gen. Chu Van Tan, a hero of wars against the Japanese and the French who helped to found the Vietnamese Army, and Gen. Le Quang Ba, former head of a commission that represented Vietnamese minorities.

Despite these moves, diplomats here say they see no serious divisions within the government.

"They have been together for 40 years," said one. "They have their differences but they are easily papered over."

The emergence recently of Thach as a major government spokesman to the world and his reputedly growing influence within the government has led to speculation that his boss, Foreign Minister Nguyen Van Trinh, is also on a purge list. But diplomats said he has been quietly moved aside, without dishonor, because of age and health reasons.