The US ambassador to Thailand is under investigation for royal defamation over comments he made criticising lengthy jail sentences from the kingdom’s lese majeste law, a foreign media group and police said Wednesday.

Under Thai law, anyone convicted of insulting the king, queen, heir or regent can face up to 15 years in jail on each count.

Prosecutions have surged since the royalist Army grabbed power last year, with record breaking sentences handed down in recent months to transgressors.

The Foreign Correspondent’s Club of Thailand (FCCT), which represents international media inside the junta-run kingdom, said it had been asked to cooperate in the probe after US ambassador Glyn T. Davies delivered a speech there in November.

The body has been asked to assist the police “in an official investigation into whether comments made by US ambassador Glyn Davies at the club on 25 November violated article 112 of the criminal code, the lese majeste law,” the club said in a statement on Wednesday.

“The FCCT is cooperating with the police,” it added. A senior Thai police source confirmed to AFP that they had received a complaint.

In a wide-ranging talk to the FCCT, which also heaped praise on the 88-year-old Thai King Bhumibol Adulyadej, Mr Davies expressed concern at long jail terms by military tribunals for alleged lese majeste.