Tue Sep 25, 11:41 PM ET

YANGON - Myanmar's military junta ordered troops and riot police to pagodas and Buddhist monasteries Wednesday to stop the mass protests that have marked the biggest challenge to the regime in 20 years.

Authorities also imposed a night-time curfew and a ban on public gatherings -- and were reportedly arresting activists -- to prevent a repeat of demonstrations that have drawn up to 100,000 people onto the streets.

Witnesses said security forces were deployed around the Shwedagon and Sule pagodas in Myanmar's biggest city Yangon, which have been focal points for the marches led by the country's revered Buddhist monks.

The pagodas were not closed but everyone was searched before being allowed to enter.

Security was also tight around key monasteries in the city apparently in a bid to prevent the monks from assembling, witnesses said.

A dusk-to-dawn curfew was announced for Yangon and Myanmar's second city, Mandalay, to try to curb the protests, which have escalated into the most potent show of public anger against the regime in two decades.

The curfew, including the designation of Yangon as a "restricted area," and the ban on public gatherings of more than five people were to remain in effect for 60 days.

Separately, the country's most famous comedian Zaganar, who had thrown his support behind the monks, was arrested at his home during the night, a friend told AFP.

The BBC also reported the arrest of U Win Naing, a prominent pro-democracy activist.

Zaganar, along with other prominent movie stars and artists, had urged the public to support the monks and earlier this week delivered food and water to them.

Over the weekend, he had spoken on short-wave radio broadcasts into Myanmar from outside the country.

"The monks are the ones out praying for us while we're at home watching TV. I'm ashamed of us," he said in one interview.

An estimated 200 troops and riot police had already deployed late Tuesday around Yangon's city hall near the Sule Pagoda.

Earlier, the streets appeared calm as the city woke up. Children were seen going to school while shops appeared to be preparing to open as they normally would.

Some commuter buses plied the streets, although numbers have fallen since a massive fuel price hike on August 15.

The price increase triggered initial protests, but the movement took off earlier this month with the emergence of the monks, who have revered status in devoutly Buddhist Myanmar.

By drawing in ever more supporters, who often formed human chains to shield the clergy, it quickly turned into the biggest mass movement since the regime violently quelled student-led protests in 1988.

Some of the monks at Tuesday's protest in Yangon chanted "We want dialogue" or carried banners reading: "May people's desires be fulfilled."

Analysts believe the junta, which has maintained an iron rule over Myanmar for more than four decades, has held back for fear any violence against monks would spark a huge outcry.

On Saturday some protesters were allowed a glimpse of democracy icon Aung San Suu Kyi, who has been detained for most of the past 18 years, but she has since been shuttered from view again.

Pictures of the protests have gone around the world, sparking international calls for restraint from the junta and messages of support for the protesters.

US President George W. Bush ramped up pressure by imposing fresh sanctions against key regime figures and their backers.

"Americans are outraged by the situation in Burma, where a military junta has imposed a 19-year reign of fear," he told the UN General Assembly.

"The ruling junta remains unyielding, yet the people's desire for freedom is unmistakable."

British Foreign Secretary David Miliband said the situation would improve when Aung San Suu Kyi, whose opposition party won 1990 elections but was never allowed to govern, "takes her rightful place as the elected leader of a free and democratic Burma."

China, one of the regime's closest allies, called for stability but said it would stick to its policy of non-interference.