Thailand's Court of Appeals has affirmed a two-year prison sentence for a prominent anti-government activist convicted of defaming the country's prime minister in 2009.

The lawyer for Jatuporn Prompan said he was granted release on bail of 200,000 baht ($5,680) pending a further appeal to the Supreme Court.

Jatuporn is a leader of the United Front for Democracy against Dictatorship, also known as the Red Shirts, which supports ousted Prime Minister Thaksin Shinawatra. It opposes the current ruling junta and advocates voting against a draft constitution in an upcoming referendum.

Jatuporn was found guilty on two counts of defaming then-Prime Minister Abhisit Vejjajiva by saying he had ordered soldiers to kill protesters and interfered with a petition for a royal pardon for Thaksin, who was convicted of corruption in 2008.