Two members of a doomsday cult are reported to have committed suicide, prompting officials to repeat warnings about the sect and raising fears of a return to tighter controls on unauthorised religious activity.
This week's deaths followed an incident last month when three other cult members refused medical treatment and starved themselves to death as part of a ritual designed to test their faith.
Authorities, stung by the deaths, broke up meetings of the so-called Chinese Dragon Buddha cult and fined members for illegal assembly.
Local media reported this week that senior cult member Vie The Vinh, 46, and Pham Van Cuong, 23, had taken their own lives to escape a disaster their sect believes will destroy the world next year.
"I have found a way to avoid the year 2000 disaster. Many people do not believe me so I will let them stew in their own juice," Vinh was said to have told neighbours before hanging herself.
Cuong died after drinking pesticide, apparently to be with Vinh in the afterlife promised to cult members.
The rise of the sect and gatherings of hundreds of thousands of people at recent Buddhist festivals suggest a surge in spiritual awareness which Hanoi officials acknowledge is taking a stronger grip on Vietnam.
Attendance at Catholic masses is also increasing and Pope John Paul at the weekend identified Vietnam as one of several Asian countries targeted for a new evangelical push next century.
"Churches and temples are more crowded," said Nguyen The Doan, director of the international relations department of the Government's Committee for Religious Affairs.
"When life gets easier, there is more time for spiritual thought. Also, the market economy has driven people to think about luck. But with little access to scientific information, they find religion," he said.
Foreign diplomats acknowledge that the ruling Communist Party has become less concerned about religious groups. But according to one source the party still sees groups which operate outside the system as potential threats to its monopoly on power.
"Many cadres remain conservative and doctrinaire, particularly in the countryside. They see any group outside the party as likely to challenge both tradition and their own privileged positions," he said.