The first day of trial for Burma's opposition leader Aung San Suu Kyi, charged with breaking the terms of her house arrest, ended Monday with testimony from one of 22 witnesses.

The witness, police Lieutenant Colonel Zaw Min Aung, was the officer who signed the original complaint against the Nobel Peace laureate.

Security was tight outside Rangoon's notorious Insein prison, where the trial is taking place. Riot police and barbed wire lined the facility, while dozens of her supporters were reported to be outside the prison.

Aung San Suu Kyi and two female assistants were charged after an American intruder swam across a lake earlier this month and sneaked into her residence. If convicted, she faces up to five years in prison.

Aung San Suu Kyi's lawyer said the trial, which could last three months, will continue Tuesday.

The American man, John Yettaw, whose unauthorized visit triggered the proceedings, also is on trial for breaking Burma's security and immigration laws.

A U.S. embassy car was seen going into the prison, but ambassadors from Britain, France, Germany and Italy were not allowed in.

Rights groups and western governments say the trial is an excuse to extend Aung San Suu Kyi's house arrest, which is due to expire at the end of this month.

The United Nations, Thailand, Singapore, Japan and the Philippines joined a host of western nations in expressing concern about the trial.

The European Union said the organization is ready to discuss increased sanctions against Burma, while the United States extended sanctions against the country last Friday.

Her trial comes ahead of Burma's controversial 2010 elections, which have been criticized as a sham that will reinforce Burma's military in power.

Some information for this report was provided by AFP, AP and Reuters.