The Criminal Court Friday sentenced red-shirt leader Surachai Saedan (Danwattananusorn) to two and a half years in prison for violating the lese majeste law.
Surachai, 70, is a leader of the Daeng Siam (Red Siam) group. He is also a former Thai Rak Thai parliamentary candidate.
Surachai was sued over his address to a redshirt rally at Samakkhitham Temple in Bangkok on February 5 and 6 last year.
The sentence was five years in prison, but he confessed, so the penalty was halved.
However, Surachai has also received jail terms totalling seven and a half years for three other cases, so his total jail term is 10 years.
Surachai has been detained on the lese majeste charge since February last year.