The junta said yesterday the detainees had been held during their investigation into the bombing spree, which hit tourist towns in the south, killing four and wounding dozens, including Europeans.
But today police said the group - many of whom are elderly - had in fact set up an illegal political party to overthrow the regime.
The bombs attacks were highly unusual in a country where foreigners and tourist towns are rarely caught up in the country's frequent bouts of political violence.
The group appeared at a Bangkok police station today escorted by soldiers - the first time they have been seen in public - to hear the charges against them.
Two are women and many of the men are in their 60s and 70s.
Thai media have run multiple reports quoting anonymous investigators as saying the group helped coordinate the recent attacks.
But Major General Chayaphol Chatchaidej, a senior official at the Office of Police Strategy who was at the police station to receive the suspects, told reporters they were not involved.
Instead he 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 said the network called itself the Revolutionary Front of Democracy party - a previously unheard of group.
A police statement handed to reporters listing the suspects' names and ages said the group aimed to "accumulate arms... And overthrow the government" but made no reference to last week's bomb attacks.
That means no arrests or charges have yet been announced for people directly responsible for the blasts.
Thai police and military have a history of rivalry but since the 2014 coup the military have spearheaded national security investigations.
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