Former Pheu Thai party MPs Pichai Naripthaphan and Karun Hosakul, as well as journalist Pravit Rojanaphruk have been released from the junta's custody.
Mr Pichai, formerly an energy minister, confirmed the release in his Facebook at 2.40pm on Tuesday. The post indicated he had agreed to comply with the junta's wishes.
"I have been released shortly after noon today ... Given the prevailing abnormal political circumstances, I won't be giving interviews on the economy or political impacts on it. I believe time will one day prove everything I had said. Over the next 10-20 years, we'll look back at this point in time [with a clear insight]. In the meantime, I'd like to support the government in solving the country's problems."
The former energy minister also thanked his fellow ex-MPs, as well as Human Rights Watch and other organisations, as well as the media, for reporting the news of his detention and urging his release.
Mr Pichai, a passionate critic of economic policies, was invited by soldiers on Sept 9 while Mr Karun was brought in a day later.
Pravit Rojanaphruk, a senior reporter at The Nation, was also told to report to soldiers on Sunday. He was reportedly detained in a building at the 11th Military Circle in Bangkok's Dusit district, a few metres away from the new jail for special prisoners including those of the Erawan and Sathorn bombings case.
Earlier, Pravit tweeted a lot about freedom of expression and the need to lift the lese majeste law.
The National Council for Peace and Order (NCPO) had earlier planned to file a charge of violating the junta's orders against Mr Pichai with the Bangkok military court, but later changed its mind, according to Thai media.
"The NCPO decided to give Mr Pichai another chance after being detained seven times," the reports said.
NCPO spokesman Col Winthai Suvaree said on Tuesday Mr Pichai had misled the public to think the NCPO could sway the Sept 6 constitution draft vote.
"Mr Karun gave information that was detrimental to a person either directly or indirectly, as well as to the country," Col Winthai said.
Mr Karun publicly pledged his loyalty to Thaksin after Thaksin's police rank was removed and mocked PM Prayut Chan-o-cha in his Facebook posts.
Col Winthai declined to comment on Pravit's detention, saying he did not know the details.
Responding to news Phumtham Wechayachai, another Pheu Thai MP, would be summoned for a session as well for criticising the detentions of Mr Pichai and Mr Karun, Col Winthai said it depended on the judgement of responsible officers.
"But generally we come to meet a person of interest at his house and don't detain him."
As for Nuttawut Saikuar, a red-shirt co-leader and former deputy commerce minister, who claimed an army car was parked outside his house for four days in a row, Col Winthai said patrol was a standard practice of the military and so far no one had any problem with it.
"Mr Nuttawut is a public speaker. Officers might be concerned about his safety."
Col Sirichan Ngathong, Col Winthai's deputy, added in deciding whom to call to exchange talks, the junta took into consideration his behaviours, the issues already agreed upon with him and information inconsistent with facts which might cause damage to others.
"As for calls for us to respect human rights, we maintain all NCPO orders, announcements and directives are laws. Whoever doesn't comply with the laws will have to be dealt with. This is the same in every country. It has nothing to do with rights. We have never abused our authority beyond the legal framework."