HM King Maha Vajiralongkorn will preside over the ceremony at the Ananta Samakhom Throne Hall starting at 3pm, according to an announcement issued by Prime Minister Prayut Chan-o-cha in line with a royal command.

The ceremony will include members of the Royal Family, privy councillors, Cabinet members, foreign diplomats, National Legislative Assembly (NLA) and Constitution Drafting Commission members, the Supreme Court president, heads of independent organisations, and senior military commanders and civil servants.

At the ceremony, the new charter will be presented to the King for his signature, after which it will be handed to the prime minister.

A court secretary then will read out a royal statement announcing the promulgation of the 2017 constitution.

That is to be followed by three rounds of 21-gun salutes by the Army, Navy and Air Force.