Police have held four students trying to tie white bows at public places in Bangkok as a symbolic gesture for justice and against dictatorship.
The activity is part of the White Bows for Justice campaign held by the Student Union of Thailand, starting on June 7 with the Victory Monument, Phayathai, Pratu Nam and Ratchaprasong areas in Bangkok.
According to the union's Facebook, they tied bows on Tuesday in public places on Ratchadamnoen Avenue, including the Royal Thai Army headquarters and Army Region 1 and the Democracy Monument.
When the reached the Democracy Monument, police stopped them and took them to the Samran Rat police station, saying they had violated the cleanliness law.
Lawyer Anon Nampa said police were also considering whether to charge them with violating the emergency decree of which penalty is up to two years in jail.
The union earlier issued a statement on the disappearance of exile activist Wanchalearm Satsaksit, a vocal critic of the military government.
The statement urges that he, as well as other exiles who disappeared, be released immediately and asks the government to take a clear stance on the case and take action.
Longer-term, it wants the Prevention and Suppression of Torture and Enforced Disappearances bill to be passed as soon as possible.
Pressure has mounted on Thai and Cambodian authorities to investigate the disappearance of the exile activist, who was seen taken by a group of armed men in front of his apartment in downtown Phnom Penh on Thursday.
Cambodian authorities initially refused to acknowledge it, saying they had not been informed of the incident. They made an about-turn on Tuesday and vowed to probe the alleged disappearance while denying any involvement in what a rights group claimed was an abduction.
Thai authorities, meanwhile, insisted they could not interfere with another country's business. Prime Minister Prayut Chan-o-cha on Tuesday said the government was willing to help the family but lacked information to proceed.
The general said at Government House on Tuesday that he had never heard of Mr Wanchalearm.
He said that the government would not interfere with another country's authority and investigation.
"I asked security authorities where he was. I've never heard his name. I learned that he fled to another country. I told them to find out why he fled and where he is. We know that he fled but we don't know where he is and what he has done," Gen Prayut said.
The prime minister said the government was ready to help Mr Wanchalerm's family if it could tell him where he had been. The Foreign Ministry was looking into the matter, he said.
Sitanan Satsaksit, Mr Wanchalaerm's sister, on Tuesday submitted a letter to Move Forward Party MPs, asking for their help in finding her brother.
Move Forward MP Rangsiman Rome wrote on Facebook he would ask Gen Prayut about Mr Wanchalearm's case at Parliament on Wednesday if the general attends the meeting.
He would also bring up the case to the House panel on laws and justice to which he belongs at its next meeting on Wednesday. He would propose that the panel summon heads of some agencies responsible for the search such as the police chief, metropolitan police chief and consular affairs director-general to testify.
As well, the party would push through the panel the version of the Prevention and Suppression of Torture and Enforced Disappearances bill drafted by the civic sector and rights organisations for debate in the House.