Thailand's government banned gatherings of more than five people on Thursday in the face of three months of escalating demonstrations that have targeted King Maha Vajiralongkorn as well as Prime Minister Prayuth Chan-ocha.
HOW DID THE PROTESTS START?
Anti-government protests emerged last year after courts banned the most vocal party opposing the government of former junta leader Prayuth Chan-ocha.
After a pause during measures to stop the spread of the novel coronavirus, protests resumed in mid-July - pushing for Prayuth's removal, a new constitution and an end to the harassment of activists.
Some protesters went further with a list of 10 demands to reform the monarchy - demands that were cheered by tens of thousands of people at a demonstration in September.
Protesters say they do not seek to end the monarchy, only reform it, but conservatives are horrified by such attacks on an institution the constitution says is "enthroned in a position of revered worship".
WHAT IS THE GOVERNMENT DOING?
Until Thursday, the government had said protests would be tolerated but that they must keep within the law.
That changed suddenly after it accused jeering protesters of obstructing Queen Suthida's motorcade and as thousands gathered at Government House to demand the removal of Prayuth.
It imposed emergency measures banning gatherings of more than five people in Bangkok, forbid publication of news or online information that could harm national security and freed up police to arrest anyone linked to the protests.
Soon after the measures were imposed, riot police cleared protesters from Government House and at least three protest leaders were arrested.
WHAT DOES THE PALACE SAY?
The Royal Palace has made no comment on the protests and the demands for reform despite repeated requests.
WHO ARE THE PROTESTERS?
Most are students and young people and there is no overall leader.
Key groups include the Free Youth Movement, which was behind the first major protest in July and the United Front of Thammasat and Demonstration, a student group from Bangkok's Thammasat University, which has championed calls for monarchy reform.
Then there is the Bad Student movement of high schoolers, which also seeks education reform.
Most protest leaders are in their 20s although one of the most prominent figures, human rights lawyer Arnon Nampa, is 36.
WHAT ROYAL REFORMS DO THE PROTESTERS WANT?
Protesters want to reverse a 2017 increase in the king's constitutional powers, made the year after he succeeded his widely revered late father King Bhumibol Adulyadej.
Pro-democracy activists say Thailand is backtracking on the constitutional monarchy established when absolute royal rule ended in 1932. They say the monarchy is too close to the army and argue that this has undermined democracy.
Protesters also seek the scrapping of lese majeste laws against insulting the king. They want the king to relinquish the personal control he took over a palace fortune estimated in the tens of billions of dollars, and some units of the army.
WHY ELSE ARE THEY UNHAPPY?
Protesters complain that the king endorsed Prayuth's premiership after elections last year that opposition figures say were engineered to keep his hands on power. Prayuth, who as army chief led a 2014 coup, says the election was fair.
Protesters have voiced anger that the king spends much of his time in Europe.
They have also challenged the spending of the Palace and lifestyle of the king, who has been married four times and last year took a royal consort.
WHAT DO THE LESE MAJESTE LAWS MEAN?
The monarchy is protected by Section 112 of the Penal Code, which says whoever defames, insults or threatens the king, queen, heir-apparent or regent shall be jailed for three to 15 years.
In June, Prayuth said the law was no longer being applied because of "His Majesty's mercy". The Royal Palace has never commented on this.
Rights groups say opponents of the government - including more than a dozen of the protest leaders - have recently been charged under other laws such as those against sedition and computer crimes.
The government has said it does not target opponents but it is the responsibility of police to uphold the law.