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 today, 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.