Police on Wednesday said they were seeking the prosecution of the leader of the new political party Future Forward over a speech he made that was posted on Facebook last June criticising the ruling junta, the National Council for Peace and Order.
The legal action against Thanathorn Juangroongruangkit, 40, and two senior colleagues in the Future Forward Party, which has attracted the support of young voters, adds to concern that the military is determined to stay in power after the March 24 election.
Mr Thanathorn and two Anakhot Mai Party executive members face five years in prison under the Computer Crime Act for "uploading false information" in a speech posted on Facebook in June last year.
A conviction would automatically disqualify all three from politics.
The party denied the charge, saying the points made in the speech were public information.
"It's obvious that as the election approaches, the case is being rushed ahead ... We're ready to face whatever challenge comes our way," Mr Thanathorn told reporters at a rally in Bangkok on Wednesday.
Hundreds of young people, many of them students, turned out for the rally. Most took pictures and videos of Mr Thanathorn and some queued up to take selfies with him.
The hashtag "#SaveThanathorn" was trending on Thai Twitter.
Mr Thanathorn has been critical of military rule, recently pledging to prosecute coup-makers and amend the new constitution.
