(Adds Rice comments on need for U.N. action) By Aung Hla Tun YANGON, Sept 24 (Reuters) - Tens of thousands of people joined Buddhist monks on marches in Myanmar's former capital on Monday in the biggest demonstration against the ruling generals since they crushed student-led protests nearly 20 years ago. "I'm very excited and frankly I'm worried too," a teacher said as she watched the massed opposition in Yangon to 45 years of army rule that has impoverished the Southeast Asian nation of 53 million people. A senior U.S. official said President George W. Bush would announce new sanctions against Myanmar's rulers and call for support for political change in the country formerly known as Burma during a speech at the United Nations on Tuesday. The European Union urged Myanmar's military junta to show the "utmost restraint" in dealing with the demonstrations. "We hope that the regime will use this opportunity to launch a process of real political reform," said Cristina Gallach, spokeswoman for EU foreign policy chief Javier Solana. Protests were reported elsewhere in Myanmar, with residents of Sittwe saying it seemed the entire northwestern coastal town of more than 100,000 people was marching with the monks. "I've never seen such a big crowd in my life," one said. In Mandalay, 10,000 monks and people took to the streets. A demonstration also took place in Bago, just north of Yangon. There were no signs of trouble but rumors of an imminent crackdown swirled. The junta, which had been silent since the monks' protests began six days ago, threatened them with legal action. State radio quoted the minister for religious affairs, Brigadier General Thura Myint Maung, as telling senior members of the State Monks Council that the protests were incited by "destructive elements who do not want to see peace, stability and progress in the country." LOCKING ARMS Five columns of maroon-robed monks, one stretching more than a kilometre (nearly a mile), marched from Yangon's Shwedagon Pagoda, the devoutly Buddhist country's holiest shrine, to the city center amid thousands of supporters. "People locked arms around the monks. They were clapping and cheering," a witness said. Some monks carried placards calling for "Better Living Conditions" and the "Release of Political Prisoners." Another banner said: "May The Peoples' Desire Be Fulfilled." After holding prayers at the Sule Pagoda in the business district, a crowd estimated at up to 100,000 marched to another pagoda and dispersed peacefully. For the first time, the marchers included members of parliament elected in 1990 from the opposition National League for Democracy (NLD), two days after a dramatic appearance of support for the monks by detained NLD leader Aung San Suu Kyi. Beyond fresh U.S. sanctions, White House national security adviser Stephen Hadley said Bush "is going to announce that there will a visa ban to key individuals associated with the negative activities of the regime, including their families." Secretary of State Condoleezza Rice said the United States would step up pressure for action on Myanmar by the U.N. Security Council to support the demonstrators. "The international community's got to stand up much more than it has," Rice told Reuters. "What the Burmese junta is doing is just a reminder of how really brutal this regime is." The Security Council has been divided over Myanmar. China and Russia, arguing that the council was exceeding its mandate, in January vetoed a resolution calling on the junta to stop persecuting minority and opposition groups and to take concrete steps toward democracy. U.N. Secretary General Ban Ki-moon's spokeswoman issued a statement urging Myanmar's government to show restraint and commending the demonstrators for taking a peaceful approach. Ban called on the junta to "seize this opportunity to engage without delay in dialogue with all the relevant parties to the national reconciliation process," the statement said. "IT'S ABOUT REFORM" What began as anger at sudden, steep fuel price rises last month has become a wider movement against the generals. "There's no prospect now of the monks just deciding to abandon this. They are getting braver every day and their demands are getting greater every day, and it's much more overtly political," a Yangon-based diplomat said. "It's now about Aung San Suu Kyi, it's about reform," the diplomat said. "The monks have got numbers and, if not immunity, then certainly it's much more difficult for the government to crack down on them than ordinary civilians." Myanmar's regional neighbors, long frustrated by the junta's refusal to speed up reforms, looked on with worry. "We hope that the ongoing protests will be resolved in a peaceful manner," said the Foreign Ministry of Singapore, one of Myanmar's biggest foreign investors. The generals were due to hold a quarterly summit soon in their new capital of Naypyidaw, carved out of the central jungle. Dealing with the protests is sure to top the agenda. The protests began on Aug. 19 and soon prompted a round-up of the democracy activists who organized them and now face up to 20 years in jail. As the protests have grown, they have drawn public declarations of support from the famous. The country's biggest stars of the stage, screen and music, including Tun Eindra Bo -- Myanmar's equivalent of Angelina Jolie -- have formed a "Sangkha Support Committee" and pledged to provide the monks with whatever assistance they need. (Additional reporting by Ed Cropley in Bangkok and Patrick Worsnip, Matt Spetalnick and Paul Eckert in New York)
