Thai King Maha Vajiralongkorn inherited one of the world's great fortunes when he ascended the Thai throne following the October 2016 death of his father

Thailand's king has been granted full ownership of the palace's multi-billion dollar assets under a law passed last year, according to a rare "explanatory note" published by the financial arm of the powerful but secretive monarchy.

King Maha Vajiralongkorn inherited one of the world's great fortunes when he ascended the Thai throne following the October 2016 death of his father, who ruled for seven decades.

Analysts say the Chakris are one of the world's richest royal dynasties, with estimates varying between $30-60 billion, although the monarchy does not publicly declare its wealth and is shielded from scrutiny by a draconian lese majeste law.

Most of the money is controlled by the opaque Crown Property Bureau (CPB), a vast portfolio that includes massive property ownership and investments in major companies.

But last July the Thai junta amended a royal property law for the first time in 69 years to give Vajiralongkorn full control over the CPB.

It is one of several steps taken by Vajiralongkorn to increase his personal control over the palace bureaucracy and its wealth since taking the throne.

The amendment means "all 'Crown Property Assets' are to be transferred and revert to the ownership of His Majesty, so that they may be administered and managed at His Majesty's discretion," according to a note featured prominently on the front page of the CPB's website.

The document was not dated and the CPB, which rarely grants interviews, could not be reached for further comment.

The note clarified that all of the CPB's shareholdings will also "be held in the name of His Majesty."

The CPB has major investments in some of Thailand's largest companies, such as Siam Commercial Bank and Siam Cement Company.

The note also said that previously tax exempt CPB assets will now be liable to taxation "in line with His Majesty's wishes."

Public discussion of the monarchy's actions remains taboo due to Thailand's lese majeste law, which punishes any perceived criticism with up to 15 years per offence.

All media based in Thailand must self-censor when reporting on the monarchy to avoid violating the lese majeste law.