Nyi Nyi Aung was charged with fraud and forgery but no charges of inciting unrest, of which he was earlier accused, were leveled, said his lawyer, Nyan Win. The fraud and forgery charges each carry a prison term of seven years.
A hearing has been scheduled for Oct. 23 with testimony by prosecution witnesses, including immigration officials, the lawyer said.
Authorities arrested the U.S. citizen, also known as Kyaw Zaw Lwin, on arrival at Yangon airport on Sept. 3.
"Nyi Nyi Aung is well and in good spirits," said Nyan Win. A U.S. Embassy consular official was also present in the courtroom inside Yangon's notorious Insein prison.
Nyan Win said Nyi Nyi Aung told him and another lawyer, Kyi Win, on Monday that he was physically tortured while being interrogated during the early part of his detention. He denied allegations by authorities about alleged plots to create unrest.
The U.S. Embassy said it has made a formal complaint to Myanmar's military government based on claims by the accused that he was mistreated in prison.
Myanmar authorities accused Nyi Nyi Aung of entering Myanmar to stir up protests by Buddhist monks, who earlier spearheaded pro-democracy demonstrations in 2007 that were brutally suppressed by the junta. Authorities said he confessed to plotting with dissident groups outside the country, and accused him of links to several activists inside Myanmar who planned to set off bombs.
Nyan Win said his client was charged with forgery for allegedly making a national identity card.
Lawyers Nyan Win and Kyi Win led the legal team that defended pro-democracy leader Aung San Suu Kyi in a recent high-profile trial that resulted in an extension of her house arrest. She is currently serving an 18-month sentence after previously spending 14 of the past 20 years in detention.
Nyi Nyi Aung's mother is serving a five-year jail term for political activities and his sister was sentenced to 65 years in prison for her role in the 2007 pro-democracy protests, activist groups and family members said.