Police arrested a student leader on Tuesday as part of a continued crackdown against political activists who helped organise an anti-government protest in July.
Jutatip Sirikhan, 21, the president of the Student Union of Thailand, was arrested by a plain-clothes police officer while she was in a taxi travelling to a university in Bangkok, a video shot by Ms Jutatip and posted on her personal Facebook page showed.
The officer identified himself as a member of the Bangkok Metropolitan Police in the video before citing a court's arrest warrant.
"We were acting on a warrant for the July 18 protest," a police officer at Samranrat Police Station in Bangkok said by telephone.
Ms Jutatip will be charged with breaching internal security and coronavirus regulations banning public gatherings among other charges, the officer said.
Ms Jutatip was also expected to be charged with sedition in connection with the July 18 demonstration by the Free Youth group at the Democracy Monument in Bangkok.
Court warrants have been issued to arrest 15 democracy activists and 14 have now been arrested, including Ms Jutatip. Police have also issued summonses for 15 other activists and all have reported to police stations.
Parit "Penguin" Chiwarak, a Thammasat University student and a core member of the Free Youth group, posted a message on his Facebook page yesterday afternoon about Ms Jutatip's arrest and urged her supporters to gather at Samranrat Police Station to give her moral support.
Student groups have rallied almost daily across the country since July 18 calling for an end to military rule. Those arrested so far have all been released on bail.