BANGKOK (AFP) - A senior Thai palace aide who served the now disgraced ex-wife of the Crown Prince was arrested on Thursday under the country's controversial lese majeste law, part of an ongoing probe that has decimated the former princess's family.

Montri Sotangkul, 53, was a member of the household staff of Srirasmi, Crown Prince Maha Vajiralongkorn's former wife.

He is accused of defaming Thailand's monarchy by improperly using his royal connections for financial gain.

He is the latest ally of the disgraced princess to be arrested in a rare public airing of palace intrigue that has seen at least eight of Srirasmi's direct relatives jailed including her elderly parents.

Montri, who continued to work at the palace after Srirasmi's downfall in December, arrived at Thailand's police headquarters on Thursday morning handcuffed and dressed in civilian clothes, an AFP photographer on the scene said, after palace officials handed him over to the police.

"Police investigators have informed him of the allegations in the arrest warrant and he signed his name to acknowledge the charges," national police chief Somyot Poompanmoung told reporters.

Police would oppose bail because Montri was considered a flight risk, he added.

It is highly unusual for palace officials to face police investigations, let alone on lese majeste charges.

Thailand's monarchy is protected by a highly controversial lese majeste law, one of the world's strictest.

Anyone convicted of insulting the king, queen, heir or regent faces up to 15 years in prison on each count.

Reporting royal defamation cases is fraught with difficulty. Even repeating details of the charges could mean breaking the law.

Critics of the law say it is frequently used to pursue political opponents of the royalist elite and their military allies.

Srirasmi has not been arrested, but she has not been seen in public since December, shortly before it was announced that she had relinquished her royal title and that Vajiralongkorn had divorced her.

Vajiralongkorn is the only son of 87-year-old King Bhumibol Adulyadej, the world's longest serving monarch, and heir to the throne.

While his father is widely adored by Thais, many of whom see him as a semi-divine figure, Vajiralongkorn has yet to attain such popularity.

Thailand has been beset by a near-decade of political turbulence - partly fuelled, analysts say, by unease over the country's future as Bhumibol's reign enters its twilight years.