Sun Sep 30, 11:13 PM ET

YANGON, Myanmar - A U.N. envoy was unable to meet with Myanmar's top two junta leaders in his effort to persuade them to ease a violent crackdown on anti-government protesters, but was allowed a highly orchestrated session Sunday with detained opposition leader Aung San Suu Kyi.

The military government, meanwhile, flooded the main city of Yangon with troops, swelling their numbers to about 20,000 by Sunday and ensuring that almost all demonstrators would remain off the streets, a diplomat said.

Scores of people also were arrested overnight, further weakening the flagging uprising against 45 years of military dictatorship. The protests began Aug. 19 when the government sharply raised fuel prices, then mushroomed into the junta's largest challenge in decades when Myanmar's revered monks took a leading role.

One protest was reported Sunday in the western state of Rakhine where more than 800 people marched in the town of Taunggok, shouting "Release all political prisoners!" Police, soldiers and junta supporters blocked the road, forcing them to disperse, a local resident said.

Ibrahim Gambari, the U.N.'s special envoy to Myanmar, was sent to the country to try to persuade the notoriously unyielding military junta to halt its crackdown. Soldiers have shot and killed protesters, ransacked Buddhist monasteries, beaten monks and dissidents and arrested an estimated 1,000 people in the last week alone.

But it was not clear what, if anything, Gambari could accomplish. The junta has rebuffed scores of previous U.N. attempts at promoting democracy and Gambari himself spoke in person to Suu Kyi nearly a year ago with nothing to show for it.

Gambari began Sunday by meeting with the acting prime minister, the deputy foreign minister and the ministers of information and culture in Myanmar's new bunker-like capital of Naypyitaw, 240 miles north of Yangon. The meeting, however, did not include the junta leader, Senior Gen. Than Shwe, or his deputy, Gen. Maung Aye, the two key figures whom Gambari had been pushing to speak with before his arrival.

He was then unexpectedly flown back to the main city of Yangon and whisked to the State Guest House. Suu Kyi was briefly freed from house detention and brought over to speak with him for more than an hour, according to U.N. officials.

Suu Kyi, the 1991 Nobel Peace prize winner who has come to symbolize the struggle for democracy in Myanmar, has spent nearly 12 of the last 18 years under house arrest.

Gambari flew back to remote Naypyitaw late Sunday in hopes of a possible third meeting on Monday, an Asian diplomat said, speaking on condition of anonymity.

U.N. officials would not comment on speculation that he was carrying a letter from Suu Kyi to the junta but issued a statement that Gambari still hoped to speak with the junta's top leaders before leaving Myanmar.

The junta did not comment on Sunday's talks.

"I view this is very positive," said a second Asian diplomat who requested anonymity, citing protocol. "Hopefully, the shuttle diplomacy will bring some positive solutions to the present crisis as to the process of national reconciliation."

Suu Kyi's own party was not as optimistic. National League for Democracy secretary U Lwin told Radio Free Asia that he expects little progress from the talks because he sees Gambari as little more than a "facilitator" who can bring messages back and forth but has no authority to reach a lasting agreement.

Many see China, Myanmar's biggest trading partner, as the most likely outside catalyst. But China, India and Russia, who have been competing for Myanmar's bountiful oil and gas resources, do not seem prepared to go beyond words in dealing with the junta.

Japan, Myanmar's largest aid donor, said it is mulling sanctions or other actions to protest the junta's crackdown, which left a Japanese journalist dead, chief Cabinet spokesman Nobutaka Machimura said Monday.

Britain's ambassador Mark Canning said Gambari should stay in Myanmar "long enough to get under way a genuine process of national reconciliation."

"He should be given as much time as that takes. That will require access to senior levels of government as well as a range of political actors," Canning told The Associated Press.

The protests drew international attention after thousands of Buddhist monks joined people in venting anger at decades of brutal military rule. Some 70,000 people took to the streets before the protests were crushed Wednesday and Thursday when government troops opened fire into the crowds and raided monasteries to beat and arrest monks.

The government says 10 people were killed in last week's violence but independent sources say the number is far higher.

Truckloads of armed soldiers on Sunday patrolled downtown Yangon near recent protest sites and along the city's major streets. A nearby public market and a Catholic church were also teeming with soldiers.

The atmosphere in the city was intimidating but not always menacing. One witness said soldiers sat inside trucks and on sidewalks chatting, munched snacks or walked around looking bored.

Still, a video shot Sunday by a dissident group, the Democratic Voice of Burma, showed a monk, covered in bruises, floating face down in a Yangon river. It was not clear how long the body had been there.

People suspected of organizing this week's rallies continue to be arrested, a third Asian diplomat said on condition of anonymity, citing protocol. The diplomat estimated the total number of arrests could be as high as 1,000, including several prominent members of the NLD. Myanmar's official press Monday said 11 people, including five young university students, were arrested for taking parts in two separate demonstrations in downtown Yangon Saturday.

Those joined an estimated 1,100 other political detainees already languishing in Myanmar's jails.

On Sunday, Pope Benedict XVI joined world leaders in expressing serious concern about the situation in Myanmar. About 1 percent of the country's 54 million people are Catholics.

"I am following with great trepidation the very serious events," the pontiff said during an appearance at his summer residence near Rome. "I want to express my spiritual closeness to the dear population in this moment of the very painful trial it is going through."

The Catholic Church has ordered its clergy not to take part in demonstrations or political activities in Myanmar. Worshippers at Yangon's Catholic churches Sunday read posted bulletins from its hierarchy stating that priests, brothers and nuns were not to become involved in the demonstrations, but that lay Catholics could act as they saw fit.