Thai police have recommended that Thaksin Shinawatra, the ousted former prime minister, be prosecuted for lèse majesté - or offending the dignity of the country’s revered King Bhumibol Adulyadej - a serious criminal charge that could preclude him from ever returning to Thai political life.

The military-installed government has struggled to charge Mr Thaksin, who is in exile, with any serious case of corruption, even though widespread graft was cited as one excuse for the September military coup that ousted Mr Thaksin from power.

Sereepisut Taemeeyaves, the national police chief, said police believed Mr Thaksin committed lèse-majesté on at least three occasions, including in remarks to taxi drivers, in a national radio broadcast, and in comments to supporters.

However, the police chief declined to elaborate because of the sensitivity surrounding any public mention of the monarchy. He said prosecutors are still considering whether to file the charges, which carry a penalty of up to 45 years in jail.

Mr Sereepisut said police also believed last year’s $3.8bn (€2.9bn, £1.9bn) take-over of Shin Corp, Mr Thaksin’s family company, by Singapore’s Temasek Holdings was illegal. Authorities are preparing the case for prosecution, although the repercussions will be greater for Temasek than for Mr Thaksin.

Giles Ungpakorn, a Chula­longkorn University political analyst, and vocal critic of the coup, said prosecuting Mr Thaksin for alleged lèse-majesté “sounds like utter desperation” by the coup-makers, who are seeking to prevent the former premier from returning to politics.

“Thaksin ought to face charges of human rights abuses in the war on drugs, and the south, but then the police and the army would also be involved,” he said. “He could also face charges of corruption if they felt he had actually broken the law.”

Yet Mr Giles said a lèse-majesté prosecution of Mr Thaksin, who was poised to win an upcoming election when the military intervened, could fuel a public debate on the merits of retaining the strict law in a modern democracy.

Thai law allows criminal prosecution for any comment considered demeaning to the royal family or the monarchy, and any Thai can make a lèse-majesté accusation that the police are compelled to investigate regardless of palace approval.

The threat of criminal prosecution has long stifled public discussion or debate about the activities and role of the monarchy, even during the September coup, which many Thais believe had the backing of the palace.

The law is also used as a political weapon, with rivals hurling lèse-majesté allegations against each other, especially during last year’s political crisis.

Even King Bhumibol , who is revered by the Thai public, has expressed discomfort with the laws. In his 2005 birthday speech, he said he should not be above criticism. “Actually, I must also be criticised. I am not afraid if the criticism concerns what I do wrong because then I know,” he said. “If you say the king cannot be criticised, it means the king is not human.”

A Swiss man, jailed since December, now faces 75 years in prison after admitting five counts of lèse-majesté for spray-painting over images of the king.

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