Three people including a well-known fortune teller and a senior police officer have been arrested in Thailand under a law that protects the royal family.

The three men were heavily guarded as they were taken to a military court in Bangkok. Reporters were not allowed inside and officials would not give details of the case. Local media say the men are accused of using the royal family's name for personal benefit.

Discussion of the monarchy is extremely sensitive in Thailand. A lese majeste law makes criticism of the royal family punishable by up to 15 years in prison.

Over the past year, there has been a significant increase in lese majeste convictions, which rights groups say is part of a wider crackdown on dissent since the military seized power from a civilian government in May 2014.