WASHINGTON - The United States on Thursday called for the immediate release of Aung San Suu Kyi, as Western governments condemned new charges brought against the pro-democracy icon by Myanmar's military junta.

US Secretary of State Hillary Clinton said she was "deeply troubled" by the case laid against Aung San Suu Kyi just days before her six-year-long detention was to have expired.

"I am deeply troubled by the Burmese government's decision to charge Aung San Suu Kyi for a baseless crime," said Clinton, who called the new charges "a pretext to place further unjustified restrictions on her."

The democracy activist has been charged with breaching the terms of her house arrest in a bizarre incident in which a US man swam to her lakeside house and hid inside her home.

Aung San Suu Kyi, now removed from her home, is being held at the grounds of Insein Prison, where the Myanmar government said she faces trial on Monday.

UN chief Ban Ki-moon is "gravely concerned" about the case, his deputy spokesman Marie Okabe said in a statement, adding Ban believed the democracy activist "is an essential partner for dialogue in Myanmar's national reconciliation."

In Geneva, the UN special rapporteur on human rights in Myanmar, Tomas Ojea Quintana, called for Aung San Suu Kyi to be freed, and said her detention broke the country's laws.

French Foreign Minister Bernard Kouchner and human rights minister Rama Yade issued a joint statement condemning the arrest "in the strongest terms."

Piero Fassino, the European Union's special envoy to Myanmar, said the international community should use "every possible means to press for the release" of the Nobel Peace Prize winner, as well as "the 2,000 other political prisoners who are held in Burmese jails."

British Prime Minister Gordon Brown, meanwhile, said the junta, which has kept Aung San Suu Kyi, 63, under prolonged house arrest, was eager to grasp any excuse to extend her detention.

"The Burmese regime is clearly intent on finding any pretext, no matter how tenuous, to extend her unlawful detention," Brown said in a statement, adding that the move did not bode well for next year's elections in Myanmar.

Canada also joined the chorus of global protest, urging Myanmar to release all political prisoners and specifically naming Aung San Suu Kyi.

"Our government is alarmed by the charges laid against Aung San Suu Kyi, and we call for her immediate release, along with all political prisoners in Burma," Canada's Minister of State for Foreign Affairs Peter Kent said.

"We strongly urge the Burmese authorities to provide appropriate medical care for Aung San Suu Kyi and for all inmates held unjustly in its prisons."

Aung San Suu Kyi appeared with her two maids in court at the notorious prison near Yangon, hours after police whisked her away from the residence where she has been held for most of the past two decades.

Stopped by the junta from taking power after winning an election in 1990, she now faces a maximum jail term of five years which would stretch her detention past its supposed expiry date this month and through the 2010 elections.

There was no immediate response to her new arrest from the Association of Southeast Asian Nations (ASEAN), the regional bloc which includes the country formerly known as Burma.

Calls and emails to the Jakarta secretariat of ASEAN were not immediately answered and there was no immediate official reaction from Myanmar's eastern neighbor and ally China, nor any Asian governments.

ASEAN has long been wary of criticizing Myanmar, but the 10-nation club has found itself embarrassed by the regime, led by the reclusive General Than Shwe.

During an ASEAN summit in Thailand last month, Myanmar threatened to boycott a meeting with human rights advocates if a Myanmar activist was present. The activist was not allowed into the session.

In Japan, meanwhile, dozens of pro-democracy campaigners rallied to demand her release.

"Free Suu Kyi!" chanted more than 60 expatriates from Myanmar in front of the country's embassy in Tokyo, holding banners that read: "The military junta should stop oppression with its unfair trial!"