The government is hunting down a group of Thai "separatists" fleeing prosecution for sedition and lese majeste to a neighbouring country, Deputy Prime Minister Prawit Wongsuwon says.
Gen Prawit, who also serves as defence minister, said the group comprises those who have fled prosecution for sedition under Section 116 of the Criminal Code and for lese majeste under Section 112.
The group is now holed up in Laos, Gen Prawit said. He identified a person behind the "separatist movement" as Chucheep Cheewasut.
The government would ask authorities in Laos to help stifle any support for the movement.
Gen Prawit, who is in charge of national security enforcement, claimed Tuesday that those arrested are part of a network of outlaws that had fled to Laos to evade charges of sedition and lese majeste.
"They come from one source, which is from the Laos side, and they also have a network in Thailand," Gen Prawit said to reporters.
"They sell shirts and flags. We've arrested three or four of them now. Whoever we can get to, we will arrest them all," he said, adding "They are traitors."
Gen Prawit responded to questions about the detention of a woman who allegedly sold T-shirts with the logo of the "Thai Federation" on them.
He said the group has a network in Thailand and its activities include selling T-shirts and flags bearing the symbol of the separatist movement.
Three or four people suspected of having links with the group had been arrested, and anyone else involved with the movement would also be detained.
"They are rebels," Gen Prawit said.
The movement used social media to propagate the idea of separatism and a new federal state, he said.
Prime Minister Prayut Chan-o-cha said that the constitution stipulates Thailand is an indivisible kingdom.
He said their arrests were necessary.
"Thailand is not a federation," he said. "We are a democratic constitutional monarchy and it is stipulated in the constitution that we are one indivisible kingdom.
"But a federation divides into many states, which Thailand does not. And the Thai flag is the tricolour flag. So can their actions be considered treacherous?" he asked reporters rhetorically.
Any effort to establish a "Thai Federation" goes against the charter and will be punished severely under the law, the prime minister added.
Col Burin Thongpraphai, a legal official of the National Council for Peace and Order, handed the woman identified only as Wannapa, who allegedly sold the T-shirts, over to the Crime Suppression Division (CSD) Tuesday for legal action.
She was charged with ang-yee (running an illegal secret organisation).
She will be taken to the Criminal Court today where police will request to extend her detention.
National Human Rights Commissioner, Angkhana Neelapaijit, and a lawyer from the Thai Lawyers for Human Rights Centre also went to the CSD to give legal advice to Ms Wannapa. Ms Angkhana said she wanted to ensure that Ms Wannapa is properly treated in compliance with human rights principles. Ms Wannapa insisted that she did not know that the T-shirts were illegal.
She was arrested at a house in Samut Prakan last Thursday. She was taken to the 11th Military Circle in Bangkok's Dusit district where she was then detained for questioning before being handed over to the CSD.
According to her husband, the 30-year-old is a motorcycle taxi driver from the northeastern province of Maha Sarakham, and has two sons aged 9 and 14.
Her husband said she intended to sell the T-shirts to supplement their income, and she was not aware of the logo's significance and had never attended any political gatherings.
Under NCPO Order No.3/2015, officers are granted the authority to detain people for questioning for up to seven days.