YANGON, Feb 19, 2010 - A Myanmar prison court sentenced a Buddhist abbot to seven years in prison, an opposition source said Friday, as a UN rights envoy wrapped up a visit to the military-ruled nation.

Gaw Thita was arrested in August as he returned from a trip to Taiwan and convicted at Yangon's notorious Insein Prison on Wednesday on three charges including unlawful association, the source said.

"He was sentenced to seven years' imprisonment on Wednesday at a special court in Insein Prison," Aung Thein, a former lawyer for the opposition National League for Democracy party, told AFP.

"He was sentenced to three years under the Immigration Emergency Act, two years under the Unlawful Association Act and two years under the Foreign Exchange Regulation Act. He has to serve the prison terms concurrently," he said.

Seven other monks arrested with Gaw Thita on August 26 at Yangon International Airport were later released without charge and the reasons for his initial detention were not clear, Aung Thein said.

"His lawyer says he will appeal for U Gaw Thita soon," Aung Thein said. U is a Burmese-language term of respect.

"He did not break any immigration law as he used his valid passport. Also there was no evidence of unlawful organisation," he said.

Myanmar's military regime has handed out dozens of tough jail sentences to people involved in the so-called "Saffron Revolution" led by Buddhist monks in 2007.

At least 31 people were killed as security forces cracked down on protesters after the biggest threat to the junta's grip on power in nearly two decades.

The sentencing came during a visit to Myanmar by UN envoy Tomas Ojea Quintana, who is in the country to inspect the regime's progress on human rights ahead of elections promised later this year.