Jailing former editor Somyot Prueksakasemsuk for lese majeste has undermined freedom of expression and is a setback to human rights, says the UN High Commissioner for Human Rights.
Navi Pillay said yesterday she was deeply concerned by the 10-year prison term handed to the former Voice of Taksin magazine editor on Wednesday.
"The court's decision is the latest indication of a disturbing trend in which lese majeste charges are used for political purposes," Ms Pillay said.
The High Commissioner also expressed concern over the length of Mr Somyot's pre-trial detention and repeated bail denials.
"I am disturbed that Mr Somyot has been denied bail and presented in court on several occasions wearing shackles as if he were some kind of dangerous criminal," she said.
Ms Pillay said she supported efforts made by some MPs and academics to propose amendments to Section 112 of the Criminal Code _ known as the lese majeste law _ to address concerns about how it is applied.
The Washington-based think-tank, Freedom House, also denounced the verdict and called for Mr Somyot's immediate release.
It urged the government to amend laws to protect free expression in accordance with international human rights standards.
"It is deeply concerning that free speech advocates like Mr Somyot are targeted, detained, and meted out sentences such as this," said Sue Gunawardena-Vaughn, director of Southeast Asia programmes at Freedom House.
The government's prosecution of speech critical of the monarchy stifles open debate and contributes to Thailand's depressed ratings in Freedom House's annual surveys, she said.
Retired professor of history Benedict Anderson said he was disturbed to learn the editor, not the writer of the articles deemed defamatory, was punished.
The academic, who has a keen interest in Thai contemporary politics, said the issue should be raised during the Bangkok governor campaign.
Meanwhile, rights activists plan to protest against the verdict by burning law books outside the Criminal Court on Ratchadapisek Road today.
Sukunya Prueksakasemsuk, Mr Somyot's wife, said she was deeply saddened and shocked by the sentence and the court's decision to deny bail to her husband.
She said Mr Somyot wanted to stay at the Bangkok Remand Prison instead of being moved to the Lak Si temporary prison for political prisoners.
Elsewhere, red-shirt supporters gathered on Wednesday night at a clock tower in downtown Chiang Rai to demand Mr Somyot's release.
They lit candles and released 11 lanterns into the air. They said the candles were to "illuminate" Thailand, which they say is still in the dark.
The released lanterns symbolised the freeing of Mr Somyot, they said.