Pro-democracy leader Aung San Suu Kyi went on trial Monday, as hundreds of riot police ringed Burma's most notorious prison to block protesters from proceedings that could send her to jail for five years.

Suu Kyi, who has already spent more than 13 of the last 19 years in detention, has been charged with violating the conditions of her house arrest by sheltering an American man who swam to her lakeside home to secretly visit her earlier this month.

The ambassadors of Britain, France, Germany and Italy as well as an Australian diplomat were barred from entering the prison, but the U.S. consul was allowed into the prison compound since the intruder — American citizen John William Yettaw — is also on trial.

Suu Kyi's late husband was British, but she does not have British citizenship, though she could apply for it.

More than 100 Suu Kyi supporters broke through an outer perimeter of barricades around Insein prison in Rangoon, but not the inner one that was closely guarded by armed police and government supporters. One young protester was seen being taken away by police.

Yettaw's family members have described him as well-intentioned and unaware of the problems he could cause by trying to talk with Suu Kyi, but her supporters have expressed anger at him for getting the Nobel Peace laureate into trouble. Suu Kyi's lawyers have said the 53-year-old from Falcon, Missouri, was not invited to her residence and that she told him to leave.

Nyan Win, a spokesman for Suu Kyi's National League for Democracy party and one of four lawyers representing her at her trial, said the court rejected their request to open the trial to the public and media "for security reasons." He added that they would continue to seek to have the proceeding made public.

"We are certain that we will win the case if it goes according to law because she didn't break the law," said Nyan Win, speaking at the party's headquarters. Courts in Burma, which has been renamed Myanmar by the ruling military junta, have rarely ruled in favor of Suu Kyi or any pro-democracy activists.

He said Suu Kyi "looks very fresh and alert just like before," and had asked the lawyers to tell her friends that she is well.

Suu Kyi had been scheduled to be freed May 27 after six consecutive years of house arrest, but the ruling junta was widely expected to yet again extend her detention period. International lawyers say this would have been illegal under Burma's own laws.

The latest charges are widely seen as a pretext for the government to keep Suu Kyi detained past elections it has scheduled for next year as the culmination of a "roadmap to democracy" which has been criticized as a fig leaf for continued military control.

Suu Kyi, two female party members who are her sole companions under house arrest, and Yettaw are being tried together for violating the conditions of her restriction order, which bans any visitors without official permission.

Yettaw is being tried separately for violations of immigration law and a statute covering swimming in the city's Inya Lake.

The first day of the trial heard testimony from police Lt. Col. Zaw Min Aung, the first of 22 scheduled prosecution witnesses, said Nyan Win. The officer, who signed the official criminal complaint on the case, laid out the prosecution's basic case.

"We call all political forces for Free Aung San Suu Kyi to mobilize all over Burma, by holding praying sessions in homes, places of worship ... and holding silent, peaceful rallies in front of Insein prison," said a statement from three activist groups.

The groups included an organization of Buddhist monks, who were at the forefront of the 2007 protests, which were brutally crushed by the regime.

Security forces blocked all roads leading to the prison and police were stationed at key intersections in the city. Several hundred riot police, many armed with guns, batons and shields, guarded the perimeter of Insein, where the regime has for years incarcerated political prisoners.

Suu Kyi, 63, was charged Thursday with violating the terms of her detention by sheltering Yettaw, a partially disabled Vietnam War-era veteran.

Yettaw was charged the same day with illegally entering a restricted zone, which carries a maximum penalty of five years in prison, and breaking immigration laws, which is punishable by up to one year behind bars.

Burma has been ruled by its military since 1962. The regime lost democratic elections in 1990 but did not honor the landslide victory of Suu Kyi's party.

Her latest arrest has sparked a storm of international appeals to Burma's government to free her and to restore democracy in the country.

In Brussels on Monday, foreign ministers from the European Union discussed increasing sanctions against Burma, but also sought ways to persuade China, India and other Asian countries to press the generals to free Suu Kyi.

Sweden's Foreign Minister Carl Bildt said EU nations would pressure the 10-country Association of Southeast Asian Nations, which includes Burma, when they meet next week in Hanoi, Vietnam. Past efforts to cajole the Asian group to denounce Burma have failed.

However, in unusually sharp criticism from a Southeast Asian nation, Philippine Foreign Affairs Secretary Alberto Romulo said Sunday that his government was "deeply troubled and outraged" over the "trumped-up charges" against Suu Kyi.

Activists said there would be demonstrations Monday in about 20 cities, including London, Rome, Boston and San Francisco.