A Myanmar court on Wednesday sentenced a US citizen to three years in prison for fraud and forgery, his lawyer told AFP, despite calls by 50 US lawmakers for his release.

Rights activist Kyaw Zaw Lwin, also known as Nyi Nyi Aung, was sentenced to three years in jail for forging an identity card, one year for failing to declare currency at customs and one year for violating immigration law.

"He has to serve the prison terms concurrently," said his lawyer Nyan Win, who also represents the country's opposition leader Aung San Suu Kyi.

"We will appeal the sentence," he added.

Kyaw Zaw Lwin was arrested in September and a verdict for the 40-year-old had been expected late last month but the court delayed the ruling.

In December, more than 50 US lawmakers wrote to junta chief Than Shwe, urging him to release the Myanmar-born detainee from prison amid health worries.

New York-based Human Rights watch has also called for his release and said the charges ? which Kyaw Zaw Lwin denied ? were "trumped-up" by the regime in Myanmar.

Kyaw Zaw Lwin's lawyers say he was deprived of food, sleep, medical treatment and US consular access in his first two weeks of detention.

His fiancee and his Washington-based lawyer said in December he had gone on a hunger strike to demand better conditions for political prisoners and was in deteriorating health.