By Aung Hla Tun

YANGON (Reuters) – Myanmar opposition leader Aung San Suu Kyi was charged on Thursday with breaking the terms of her house arrest and faces up to five years in jail after an American intruder sneaked into her lakeside home, her party said.

Opposition activists denounced her trial, set to begin on Monday, as a ploy by the country’s junta to keep Suu Kyi, 63, sidelined ahead of elections in 2010.

Her National League for Democracy (NLD), which won a landslide election victory in 1990 only to be denied power by the military, “strongly condemned” the new charges two weeks before her latest six-year detention is due to expire on May 27.

The Nobel Peace laureate has spent 13 of the past 19 years in detention, most of it held virtually incommunicado at her home, with her telephone line cut, her mail intercepted and visitors restricted.

She was charged under the Law Safeguarding the State from the Dangers of the Subversive Elements, which imposes a three-to-five-year jail term if a detainee “violates the restrictions imposed on them.”

The charges stem from a bizarre incident involving U.S. citizen John William Yettaw, who, according to state media, claimed to have swum across Inya Lake and spent two days in Suu Kyi’s compound earlier this month.

Yettaw was charged with abetting, or “encouraging a violation of the law,” said Aung Thein, one of Suu Kyi’s lawyers.

Other reports said he had been charged with entering a restricted zone and breaking immigration laws, but Aung Thein could not confirm those charges.

Yettaw was arrested on May 6 as he swam back from Suu Kyi’s home. U.S. embassy officials were allowed to see him on Wednesday but he revealed little about his motives.

“We cannot comment. He didn’t tell us any details,” embassy spokesman Richard Mei said.

It was apparently the second time that Yettaw — described by state media as a 53-year-old psychology student and a resident of Missouri — had tried to meet Suu Kyi at her home.

Suu Kyi’s main lawyer, Kyi Win, said Yettaw was told to leave after his first attempt in late 2008. This time Yettaw refused.

“He said he was so tired and wanted to rest, but she pleaded with him. Then he slept overnight on the ground floor,” Kyi Win told the Democratic Voice of Burma (DVB).

“GRAVE AND CONCERNING”

Suu Kyi’s detention in a house inside the prison will renew fears for her health after she was put on an intravenous drip last week for dehydration and low blood pressure.

Her main doctor, Tin Myo Win, was detained last week and is still being held at an undisclosed location.

The United Nations has said Suu Kyi’s continued house arrest is illegal under Myanmar law, which permits detention for five consecutive years before the accused must be freed or face trial.

Suu Kyi lodged an appeal against her detention after it was extended last year in an apparent violation of the law. The junta denied the appeal, saying they could hold her for a sixth year.

“The regime filed these charges to extend her detention beyond the six years,” said Aung Din, executive director of the U.S. Campaign for Burma, a pro-democracy group.

“It is an act of blackmailing the international community, especially the United States, demanding a ransom to get back an American citizen and better treatment for Daw Aung San Suu Kyi.”

Australia’s Foreign Minister Stephen Smith called the arrest “grave and concerning” and demanded her immediate release.

The 10-nation Association of South East Asian Nations (ASEAN), one of the few groups that allows Myanmar as a member, is “concerned” by the latest events there, Thai Prime Minister Abhisit Vejjajiva told Reuters.

“We would like to see positive steps being taken according to the roadmap. It’s very important the political process is inclusive,” he said.

The generals have in the past ignored calls for her release as they push ahead with a seven-step “roadmap to democracy” expected to culminate in the multi-party elections in 2010.

The NLD and Western governments dismiss the “roadmap” and last year’s army-drafted constitution as a cover for the generals to cement their grip on power.