Foreign diplomats said Wednesday's demonstrations at two Yangon university campuses ended without incident but that scores of riot police remained on stand-by.

``It's obviously building up again,'' said one western envoy. ``There is tension there and it will only take a small spark to set it all off again.''

Up to 4,000 students joined the protests, which came amid escalating political tensions after the Opposition National League for Democracy said it would convene a parliament which was elected in 1990 but has never been allowed to sit.

``End the military government,'' chanted up to 800 students at the Yangon Institute of Technology (YIT), as riot police cordoned off a one-mile perimeter around the campus, witnesses said.

Another 3,000 students rallied at the Hlaing campus in the city, where many of Theinstitution's students live, diplomats and witnesses added.

Riot police were sent to Hlaing and more were deployed around the main YIT campus, they said. Riot troops were also seen entering the YIT but there were no reports of clashes.

After being counselled by academics, all but a few of the students agreed to board buses to take them to their homes at Hlaing and elsewhere.

The Hlaing protest died down in the early hours of Thursday and all was later reported quiet, witnesses said.

``There's nothing happening at the moment,'' said another western diplomat. "But it's got to flare up again. It's just a matter of when and to what degree.''

The Hlaing campus, which was also sealed off by security forces, hosts a college for students preparing to enter YIT.

The protest was initially triggered by student anger at arrangements for examinations over the last two weeks, the first since universities were closed following unrest in December 1996, diplomats said.

But the demonstrations were the biggestsince the 1996 unrest and came after Riot police broke up a smaller protest outside Yangon University on August 25, arresting dozens of people, according to witnesses.

Another protest was staged later that day at YIT, during which rocks were thrown and riot police mobilised.

``The government is handling these things pretty well,'' said one diplomat.

``They are trying to avoid violence and confrontation because they know that is only a short-term solution. Obviously, there must be change in Myanmar. But at least the process is peaceful at the moment.''

Political tensions are rising following an Opposition decision to convene the parliament elected in 1990 after the junta ignored earlier requests to do so.

The Opposition, led by the NLD of Nobel peace laureate Aung San Suu Kyi, won the1990 polls by a landslide but the junta has refused to relinquish power.

The junta has stepped up its verbal offensive against the Opposition, saying its vow to convene parliament was an unacceptable threat to nationalsecurity and promising stern action if the plan went ahead.

The military also repeated allegations that foreign governments were supporting the NLD and using sanctions to hinder progress toward democracy.