Fourteen detained student activists have been brought before a military court in a case that has attracted international calls for their release and criticism of the military junta's strict controls on freedom of speech and assembly.

The university students were arrested June 26 on charges of sedition and violating the junta's ban on political gatherings for holding a peaceful anti-coup rally in Bangkok.

Each student faces a maximum of seven years in prison.

On Tuesday, a military court was to decide whether to extend their pre-trial detention for another 12 days. Journalists weren't allowed to enter the courtroom.

Since overthrowing an elected government in May 2014, Thailand's military rulers have jailed opponents who dared to speak out against them. They've censored the media, dispersed protesters and forbidden open political debate.