A Swiss man has been sent to prison for 10 years for defacing posters of King Bhumibol Adulyadej of Thailand.

Shackled and dressed in an orange prisoner's uniform, Oliver Rudolf Jufer remained expressionless as he was punished under Thailand's strict laws that forbid the insulting of the monarchy. He was told by the judge that he had received a lenient sentence for admitting his crimes.

Jufer, 57, changed his plea and admitted five counts of lèse-majesté, or insulting the monarchy, at a hearing in Chiang Mai two weeks ago. He faced a maximum sentence of 75 years in prison. His trial and hearings have been conducted in secret to spare any more offence for King Bhumibol, Thailand's 79-year-old ruler.

Ushered out of the court and into a prison to begin his sentence, Jufer made no comment to waiting reporters. He has a month to appeal the sentence, although his court-appointed lawyer, Komkrit Kunyodying, called the punishment “appropriate for the crime he has committed”.

Jufer, who has lived in Thailand for 10 years, is the first foreigner to be convicted under the country's feudal laws of lèse-majesté, which make it a treasonable offence to insult or criticise the monarchy, for at least a decade. Other foreigners accused of the crime in recent years have been deported.

He admitted defacing posters of King Bhumibol when he was shown CCTV footage of him drunkenly vandalising signs on the night of Dec. 5, the king's birthday, last year. Chiang Mai's shops and bars had closed early to honour the occasion with fireworks and prayers, leaving Jufer unable to buy alcohol.

According to testimony read in court today, Jufer had been drinking with a friend and drove his motorcycle home to pick up a can of spray paint, which he had bought to redecorate his dog house. He then drove to a municipal office where a large poster of the King was hung, and climbed a ladder to ruin the image.

He went on to splatter four other posters near his home, according to the testimony.

King Bhumibol, the world's longest reigning monarch, is greatly loved by Thais and regarded by some as semi-divine. He became a critical source of authority during last year's constitutional crisis, during which the Thai Prime Minister, Thaksin Shinawatra, was first weakened by protests and then deposed by a military coup.

The country's lèse-majesté laws, intact since the first writing of Thailand's criminal code in 1908, attract occasional international criticism but Switzerland today said it would not ask the government to release Jufer, who is married to a Thai wife.

Nonetheless, a spokesman for the Swiss Foreign Ministry observed that "legislation on the basis of which our compatriot was tried is applied with great rigour." Jufer faced sentences of between 3 and 15 years for each count.

“The Swiss government does not intervene with authorities in cases where the procedure followed conformed to basic judicial principles,” the Swiss spokesman told AFP. “Our compatriot was arrested on the basis of clearly established legislation. He knows why he was arrested, he had the assistance of a defence lawyer and he has the possibility to appeal."