* Strict laws in Thailand prohibit debate on monarchy
* Rights groups and EU condemn sentence (Adds comment from UN Commissioner paragraphs 6,7)
By Amy Sawitta Lefevre
BANGKOK, Jan 23 (Reuters) - A former Thai magazine editor was jailed for 10 years on Wednesday for insulting the royal family under the country's draconian lese-majeste law, a sentence that drew condemnation from international rights groups and the European Union.
Somyot Prueksakasemsuk was found guilty of publishing articles defaming King Bhumibol Adulyadej in 2010 when he was editor of a magazine devoted to self-exiled former Prime Minister Thaksin Shinawatra.
The articles criticised the role of a fictional character meant to represent the king, public prosecutors said in a July 2011 report. Discussions about the role of the monarchy are forbidden.
"The accused is a journalist who had a duty to check the facts in these articles before publishing them. He knew the content defamed the monarchy but allowed their publication anyway," a judge said in passing sentence.
The magazine, whose English title is Voice of Taksin, a play on words meaning "Voice of the Oppressed", was shut down shortly before Somyot's arrest, said Thida Thawornseth, a leader of the pro-Thaksin "red shirt" movement.
United Nations High Commissioner for Human Rights Navi Pillay described the sentence as "a setback for the protection and promotion of human rights in Thailand".
Pillay said in a statement from her office in Geneva, "The court's decision is the latest indication of a disturbing trend in which lese-majeste charges are used for political purposes."
The European Union Delegation to Thailand said the verdict and sentence undermined the right to freedom of expression.
"At the same time, it affects Thailand's image as a free and democratic society," it said in a statement.
New York-based Human Rights Watch said the ruling was "more about Somyot's strong support for amending the lese-majeste law than about any harm incurred by the monarchy".
Rights groups say the lese-majeste law is used by Thailand's powerful elite to silence political opponents, including supporters of pro-Thaksin groups.
"The lese-majeste law works against the long-term interests of the Thai monarchy," said David Streckfuss, a Thailand-based independent scholar and lese-majeste expert. "To a society that is becoming ever more politically conscious, the holding and trying of defendants seems arbitrary, petty and a clear violation of human rights."
Somyot, who was jailed for an additional year on an unrelated defamation conviction, was arrested on the lese-majeste charge while Oxford-educated, pro-establishment Abhisit Vejjajiva was prime minister.
Current Prime Minister Yingluck Shinawatra, Thaksin's sister, promised to amend the law during her 2011 election campaign but has rowed back on that since coming to office, causing divisions among her supporters.
Websites accused of defaming the royal family are frequently shut down.
"Thailand's 2007 Computer Crimes Act effectively muzzles those who want to express an honest opinion and 75 percent of websites shut down since it came into force have been because of so-called anti-monarchy content," said Sawatree Suksri, a criminal law lecturer at Thammasart University in Bangkok.
Convictions under the law carry a maximum jail term of 15 years.
The 85-year-old king, who has been in hospital since 2009, is seen by many in Thailand as a unifying, semi-divine father figure.
National unease over what follows his reign has contributed to tensions in the country since before Thaksin was toppled by the military in 2006, leaving the country divided broadly between royalists and nationalists on the one side and Thaksin's mostly lower-class supporters on the other. (Additional reporting by Aukkarapon Niyomyat and Robert Evans in Geneva; Editing by Nick Macfie and Jane Baird)