Thai police on Friday said the group of 15 suspects, who were detained by the military investigating in last week's deadly tourist resort attacks, was not involved in the blast.
The junta said on Thursday that the detainees had been held during their investigation into the series of bombings that killed four people and wounded dozens including Europeans.
The police also said that the group, including many elderly people, had set up an illegal political party to overthrow the regime.
The soldiers escorted the group on Friday at a Bangkok police station to hear the charges against them. This was the first time they were seen in public.
Meanwhile, several Thai media reports quoted anonymous investigators saying that the detained group helped to coordinate the recent attacks.
Major-General Chayaphol Chatchaidej, a senior official at the Office of Police Strategy, who received the group at the police station, said they were not involved.
"There is no evidence linking them to the bomb attacks in the seven southern provinces, based on our investigation, although some of them are involved with lese majeste and arms trafficking," he told AFP.
Chatchaidej instead described them as "a splinter faction of the anti-junta 'Red Shirt' movement loyal to ousted Thai premier Thaksin Shinawatra, who was toppled by the military in 2006".
He also said the network called itself the Revolutionary Front of Democracy party.
Thai deputy national police spokesman Kissana Phatanacharoen told reporters that only one warrant of arrest was issued for a suspect in connection with the attacks. The suspect was identified as Ahama Lengha, a Thai national from Narathiwat province near the border with Malaysia.
A police statement with a list of all the suspects' names and ages was handed to the reporters. The statement showed that the group currently faces one charge of breaching the junta's ban on political gatherings and another charge of belonging to an unlawful secret society.