Thailand has started the procedure for naming Crown Prince Maha Vajiralongkorn as the new king in the country.
Its parliament approved the sending of a formal invitation, which he has to accept before ascending to the throne.
The deeply revered King Bhumibol Adulyadej died on 13 October, plunging Thailand into mourning.
The prince was widely expected to succeed his father, but officials had earlier said he wanted to postpone it by at least a year.
The official reason given was that he wanted to give the Thai people time to mourn his father before he became king.
Correspondents say Thailand was left in an odd constitutional limbo as the prince, the undisputed heir, should have succeeded his father immediately.
In the past doubts have been expressed by senior officials over how the crown prince can perform the role played by his father for 70 years.
The monarchy occupies a pivotal place in Thailand’s political order. King Bhumibol Adulyadej had been seen as a unifying figure amid periods of political unrest, including during the most recent military coup in 2014.
