Myanmar's detained opposition leader has gone on trial at Yangon's Insein prison on charges that could extend her detention by five years.
Aung San Suu Kyi is accused of breaking the conditions of her six-year house arrest, which is set to expire on May 27.
A local official told the AFP news agency that the trial started on Monday, without giving further details.
Khin Ohmar, a political activist, told Al Jazeera that about 500 people had gathered outside Insein prison on Monday, including some US officials and youth members of Aung San Suu Kyi's National League for Democracy (NLD).
Myanmar authorities had stepped up security around the prison, with nearby shops closed and family members not allowed to visit anyone at the prison on Monday, Khin Ohmar said.
If convicted, Aung San Suu Kyi faces three to five years in prison.
The country's military rulers have detained the 63-year-old for more than 13 of the past 20 years, much of that time at her Yangon home guarded by police.
The latest charges apparently stem from an incident in which an American man, John Yettaw, was arrested early this month for allegedly swimming across a lake to secretly enter Aung San Suu Kyi's home and stay there for two days.
Yettaw, who has been charged with immigration violations, encouraging others to break the law and entering a restricted area, is also expected to stand trial.
The motives for his bid to meet Aung San Suu Kyi are unclear.
Yettaw swam to her home in November last year but the Nobel Peace laureate refused to see him.
He tried again on the night of May 3.
"This time, Daw Aung San Suu Kyi allowed him to stay at her residence until the night of May 5, 2009, spoke with him and provided him food and drinks," a police complaint said.
Kyi Win, a lawyer representing Aung San Suu Kyi, said his client told Yettaw to leave, but he refused.
She did not report him to authorities because "she did not want anybody to get into trouble because of her", Kyi Win added.
Calls for release
Jared Genser, an international lawyer also representing the opposition leader, said in a statement that it is "highly doubtful justice will be served" in the trial.
He also accused the military government of failing to provide sufficient security around Aung San Suu Kyi's home, leading to Yettaw breaking into the property.
Western governments, the United Nations and human rights groups have condemned the charges against Aung San Suu Kyi and called for her immediate release.
Former student demonstrators and monks involved in street protests that were crushed by the military in 2007 also said in a joint statement that they would "oppose this latest atrocity using any means until Daw Aung San Suu Kyi is freed".
Critics also say the charges are aimed at keeping the opposition leader in detention ahead of the government's promised multi-party elections in 2010.
The NLD won a landslide election victory in 1990 only to be denied power by the military, which has ruled the country since 1962.
"The trial is all about keeping any voices of dissent silent in the run-up to rigged elections next year," Zoya Phan of the Burma Campaign UK, an activist group seeking "human rights, democracy and development" in the country also known as Burma, told the Reuters news agency.
In neighbouring Thailand, exiled Myanmar activists marched on the country's embassy on Sunday, calling for the democracy leader's immediate release.
However, despite the international outcry, state-controlled media in Myanmar has said nothing about the trial.