Thai election authorities on Wednesday filed their first charge under a law banning campaigning and debate before a referendum on a controversial new constitution, as the junta tightens its grip on free speech.
The broadly-worded legislation, which came into force last week, mandates up to 10 years in prison for anyone criticising the military's new charter or "influencing voters" in the run-up to the August 7 poll.
It will be Thailand's first return to the ballot box since the generals toppled an elected government two years ago and banned all political activities.
On Wednesday a senior official from the election agency filed the first charge under the law against a group who posted Facebook messages aimed at "inciting voters", police said.
"I want this case to serve as an example, that from now on criticising (the charter) must be done in a polite manner," Election Commissioner Somchai Srisuthiyakorn said on TV after filing the charge.
"Those who post comments with rude or aggressive wordings are clearly violating the law," he added.
Police said the group was based in the northeastern province of Khon Kaen, a stronghold of the political bloc opposed to the junta, but refused to release the organisation's name.
Criticism of the military regime -- often posted on social media -- has landed scores of activists and former politicians in detention over the past two years, attracting frequent condemnation from rights groups and UN agencies.
On Wednesday Thai human rights lawyers said at least eight people had been "abducted" by military officers across the country.
A military spokesman told AFP a total of ten people had been arrested on computer crime charges, another broadly-worded law used to curb dissent.
Later in the day small groups of activists were dragged away by police shortly after they gathered in Bangkok to protest at the arrests and the junta's limits on free speech.
Critics accuse the military of seeking to entrench its political influence through the proposed constitution, which would give a junta-appointed senate authority to check the power of elected lawmakers for a five-year transitional period.
The senate, which would have seats reserved for military officers, could also have a say in choosing the prime minister if voters approve that power in the referendum ballot.
The military-appointed drafters of the charter insist their work will exclude corrupt politicians and provide a "safety valve" if Thailand topples into a political crisis.
The kingdom has been torn by rounds of often-deadly mass protests since billionaire premier Thaksin Shinawatra was toppled by the military in 2006.
His supporters say the junta is bent on dismantling the Shinawatras' powerful political faction, which has won every national election in the past decade but is hated by a military-allied elite.