YANGON (AFP) - Myanmar opposition icon Aung San Suu Kyi went on trial amid tight security at a notorious prison Monday, facing up to five more years in detention on charges of harbouring a US man who swam to her home. Dozens of supporters of the ailing Nobel Peace Prize laureate gathered near Insein prison outside Yangon as the hearing got under way, one of whom was arrested by the phalanx of riot police posted behind barbed wire blockades. French first lady Carla Bruni-Sarkozy on Monday appealed for the release of Myanmar opposition leader Aung San Suu Kyi who has been jailed and put on trial at a notorious Yangon prison. The wife of President Nicolas Sarkozy called on the Myanmar government to free the 63-year-old pro-democracy activist in an open letter made public by the Elysee presidential palace. Japan told Myanmar Monday it had profound concerns about the trial of the Southeast Asian nations pro-democracy leader Aung San Suu Kyi, according to the foreign ministry here. Japanese Foreign Minister Hirofumi Nakasone made the remarks in a telephone conversation with his Myanmar counterpart Nyan Win, the ministry said in a press release. The ruling junta pushed ahead with the trial of the 63-year-old despite the threat of tougher sanctions from the European Union over the charges against her, which allege that she violated the terms of her house arrest. We can definitely win according to the law. She didnt do anything wrong, Nyan Win, a spokesman for Aung San Suu Kyis National League for Democracy party, told AFP after the court was adjourned. Lawyers for the pro-democracy leader opened the proceedings with an application for the trial to be held in open court, which the judges rejected, Nyan Win said. The court then heard from the first of an expected 22 witnesses, police colonel Zaw Min Aung, who filed the original complaint against the pro-democracy leader after the incident involving the American man, he added. Nyan Win quoted the policeman as saying that Aung San Suu Kyi had violated the personal restrictions on her by having contact with John Yettaw, the man who swam across a lake to her residence earlier this month. She was wearing traditional Burmese clothing in a dark green-blue colour and did not speak during the hearing, he said. But she was alert and wanted to tell friends that she is in good health, he added. Her latest six-year period of detention was due to expire on May 27, but Yettaws visit has apparently provided the ruling generals with the ammunition they need to extend her detention past the 2010 polls. Yettaw, 53, reportedly described as a harmless eccentric by relatives in the United States, also appeared at the trial along with two aides of Aung San Suu Kyi. A US consular official attended the hearing with Yettaw, Nyan Win said. Yettaw used a pair of home-made flippers to swim across a lake earlier this month to the residence where Aung San Suu Kyi has been kept in virtual isolation for most of the last 19 years. Security forces barred the ambassadors of Britain, France, Germany and Italy from the jail as they attempted to gain entry to the court, a western diplomat said.