Public prosecutors will indict nine rally leaders who joined in a rally at Pathumwan intersection to protest against the military regime and its postponement of the election.
They have decided, however, not to indict 24 other protesters who attended the rally, saying prosecution would not be in the public interest.
The nine rally leaders will be indicted in a separate lawsuit.
Prayut Phetkhun, deputy spokesman of the Office of the Attorney-General, said yesterday public prosecutors at the Pathumwan District Court decided on Friday not to indict the 24 who joined in the rally on Jan 27.
The attorneys reasoned that although there were grounds that the group had violated the National Council for Peace and Order (NCPO)'s political ban order, the prosecutors viewed the prosecution against the 24 would not benefit the public.
The prosecutors cited the Office of the Attorney-General's regulations on "not indicting in the case that is not of public interest" issued in 2011, he said.
However, the decision is not final, Mr Prayut said adding that the prosecutors must submit the case for the final consideration of the attorney-general.
NCPO judge advocate Burin Thongprapai earlier filed a complaint against the group for allegedly violating the NCPO chief's order which prohibits political gatherings of five people or more, and holding a political rally within 150 metres of the royal compound.
There were 33 suspects in total in the lawsuit. Mr Prayut said the prosecutors have separated the case of the nine leaders and indicted them to the Southern Bangkok Criminal Court.
The leaders are Rangsiman Rome, Sirawith Seritiwat, Nattha Mahatthana, Anon Nampa, Sukrit Piansuwan, Chonticha Jaengrew, Karn Phongpraphan, Netiwit Chotipatpaisal and Ekachai Hongkangwan.
As well as violating the NCPO's political gathering ban order, the nine leaders also face charges of sedition under the Section 116 of the Criminal Code.
Meanwhile, an anti-NCPO rally took place yesterday, demanding the junta to step down and Prime Minister Prayut Chan-o-cha to remain only as chief of a caretaker government.
Joining hands and calling themselves the People Who Want Elections, the groups of activists, including some of the nine leaders of the previous protest, yesterday held a rally in the theme of "joining hands to root out the NCPO" and announced they would upgrade their demonstrations to bigger movements to oust the NCPO if their demands were not met.
"Our stance has been that the election must be held in November, and this has not changed. We can see that it's Gen Prayut's intention for the election to not happen this year," said Mr Rangsiman, a leader of the Democracy Restoration Group at yesterday's rally at Thammasat University Tha Phrachan campus which attracted a few hundred people.
"But he promised that the election will happen certainly in February 2019. Nobody believes his words as he keeps postponing it."
Mr Sirawith, also known as "Ja New", leader of the New Democracy Group, said the NCPO so far has enjoyed its time in power. But revoking the NCPO's orders and announcements would demonstrate its sincerity to hold elections.
If the NCPO does not respond to the groups' demands, they will upgrade their rally to major protest aimed at ousting the regime, Mr Sirawith said.
The groups called on political parties including Pheu Thai, the Democrats and other new parties, to join their movements.
At yesterday's rally, the iLaw group also gathered people's signatures to support a petition calling for the annulment of 35 orders and announcements issued by the NCPO which they claim violate people's rights.
Government spokesman Sansern Kaewkamnerd said the prime minister already announced that the elections would happen in February 2019.
"Your [protesters'] demand for the elections to happen today is impossible, and you know this is so. We therefore see this rally as a political expression. But the NCPO respects that it was held in an educational institution, and does not want to take too much action," he said.
"If there was no NCPO in the past, would peace and order be possible like today?" Mr Sansern said.
"You cannot just have conflicting political parties who won't stop fighting. What else could we do? The NCPO came to help," he said.