Bangkok: The United Nation`s human rights office has voiced alarm at recent arrests and jail sentences for insulting Thailand`s monarchy, warning of "chilling effects" on freedom of expression under the junta.
Since the army seized power from an elected government in May, at least 13 new royal defamation cases have been opened for investigation and other allegations have been revived, spokeswoman Ravina Shamdasani said.
"We are seriously concerned about the prosecution and harsh sentencing of individuals in Thailand under the country`s lese majeste law," she said in a statement issued in Geneva on Tuesday.
"Such measures are adding to the larger pattern of increasing restrictions on freedom of expression in Thailand."
Last week two activists were charged with breaching the strict royal insult laws during a university play in October 2013 to commemorate the 40th anniversary of a student-led uprising.
The UN said the play depicted a fictional monarch who was manipulated by his adviser.
King Bhumibol Adulyadej, 86, is revered by many Thais and protected by tough defamation laws that carry a maximum jail sentence of 15 years for each conviction.
A 28-year-old musician was recently sentenced to 15 years in jail after he was found guilty of posting insulting messages about the monarchy on Facebook.
Earlier this month, a taxi driver was jailed for two years and six months for a conversation he had with a passenger that was deemed offensive to the monarchy, the UN noted.
"The threat of the use of the lese majeste laws adds to the chilling effects on freedom of expression observed in Thailand after the coup, and risks curbing critical debate on issues of public interest," Shamdasani said.
Critics say the royal slur legislation has been politicised, noting that many of those charged in recent years were linked to the "Red Shirts" protest movement, which is broadly supportive of fugitive former premier Thaksin Shinawatra.
Thaksin clashed with the royalist establishment before his overthrow in a coup in 2006.
His younger sister Yingluck Shinawatra was ousted as prime minister in a controversial court decision in May this year, shortly before the army chief seized power in a bloodless coup.
The junta has moved to suppress any public protests against the military takeover.
New York-based Human Rights Watch said the arrests of the two activists, 10 months after the play was staged, suggested that the Thai junta was sending a "political message".
"The heavy-handed enforcement of lese majeste laws has a devastating impact on freedom of expression in Thailand," said HRW Asia director Brad Adams.
"A broad-based discussion is urgently needed to amend the laws to ensure that they conform with Thailand`s international human rights obligations."