Police say they plan to charge at least 30 people over the rallies staged outside parliament and police headquarters this week.
No decision has been made yet on whether to lay lese majeste charges against the protesters, some of whom have been calling for reform of the monarchy, said Pol Maj Gen Piya Tawichai, deputy commissioner of the Metropolitan Police Bureau.
He said 14 people had been identified while committing offences near the parliament complex in Dusit district on Tuesday, and 17 others during the protest outside the Royal Thai Police Headquarters in Pathumwan district on Wednesday.
Investigators would start calling them in to acknowledge the charges next week, he said on Friday.
The charges would include causing damage to government property, demonstrating without prior permission, assembling to create disorder, physical assault, attempted murder and violation of cleanliness and land traffic laws.
Pol Maj Gen Piya said three people who were shot during clashes between rival groups of demonstrators near parliament had been questioned. One was shot at the Bang Pho intersection and two at the Kiak Kai intersection.
The gunshot victims were from both the royalist and anti-government sides, he said, adding that the investigation was continuing.
The Erawan Centre reported earlier that six people with gunshot wounds, none of them serious, were among the 55 people injured during the clashes on Tuesday night.
In a related development, two teenaged leaders of the “Bad Student” group are facing charges for joining a banned protest on Oct 15.
Pol Maj Gen Yingyos Thepchamnong, a spokesman for the Royal Thai Police, said the two would be questioned in the presence of their parents and lawyer.
Pol Maj Gen Piya, meanwhile, said police had yet to decide on the critieria for lese majeste prosecution under Section 112 of the Criminal Code.
Anti-government demonstrators have been staging large rallies since July to demand the resignation of Prime Minister Prayut Chan-o-cha, a new constitution and reform of the monarchy.
The rallies, while generally peaceful, have become increasingly rowdy and the language aimed at the government and the monarchy increasingly rude. On Wednesday night, several obscene messages were spray-painted outside police headquarters and on the road in front of the complex.
Gen Prayut threatened on Thursday to use “all laws” against protesters who break them, raising concerns among activists that this could include Section 112, under which there have been no prosecutions for more than two years.
Gen Prayut said earlier this year that His Majesty the King had asked authorities not to use Section 112.
Another major protest is planned for Wednesday at the Crown Property Bureau on Phitsanulok Road. One of the complaints raised by protesters has involved the move by the King to take the assets of the Bureau, valued at billions of dollars, under his personal control.