Thailand faced criticism from international rights groups on Wednesday for bringing charges of insulting the monarchy against protest leaders who have challenged King Maha Vajiralongkorn as well as the government.
A police source said a total of 15 protest leaders had been summoned to acknowledge lese majeste charges over comments made at protests in September and October, when they spoke about the king's behaviour, lifestyle and spending.
"No one should be arrested or imprisoned merely for criticizing public officials or a system of government," said human rights lawyer Amal Clooney in a statement from the Clooney Foundation for Justice.
The Paris-based International Federation for Human Rights said "lese-majeste must not be used to criminalize pro-democracy protest leaders and participants".
Responding to the criticism, government spokeswoman Rachada Dhnadirek said: "The government has been open-minded to rights and freedoms despite many imprudent expressions which offend the majority. The government must used its authorised powers."
The royal insult laws have not been used since 2018 and Prime Minister Prayuth Chan-ocha said in June that they were not being used at the request of the king.
Since July, protesters have been calling for the removal of Prayuth, a former junta leader. They also demand a new constitution and curbs on the king's powers.
Summonses for protest leaders came ahead of a demonstration planned on Wednesday to call on the king to give up the personal control he took over a palace fortune valued in the tens of billions of dollars.
Protesters shifted the venue at the last minute from the Crown Property Bureau, which manages the royal assets. Police blocked roads there with shipping containers and razor wire - adding to the traffic chaos in Bangkok's rush hour.
The protest will now take place at the headquarters of Siam Commercial Bank, in which the king's stake of more than 23% makes him the largest shareholder.
"Transferring the crown property to the king's property is equivalent to a robbery of the nation's wealth," the FreeYouth protest group said, referring to a 2017 change in the law that gave the king control of the Crown Property Bureau.
Details of its assets are not made public but they are estimated to be worth more than $30 billion.