Thailand anti-coup protests
Protesters are detained by policemen during a protest in central BangkokDamir Sagolj

Thai authorities have arrested dozens of people who have attempted to stage anti-coup protests in capital Bangkok on the first anniversary of the army taking over the country.

No less than 48 people have been detained by either police or the military forces during the crackdown. The police have said many other activities have been freed after their attitudes have been "adjusted".

The demonstrations were led by the Resistant Citizens group spearheaded by anti-administration activists Pansak Srithep and Sirawitch Sereethiwat.

The activists were arrested after they filed a case against Prime Minister General Prayut Chan-o-cha, former military general, and other army leaders for launching a coup against the democratically-elected administration.

The activists said according to the Thai constitution, those junta leaders should face death penalty. The Criminal Court will decide next week whether it is taking up the case.

"This constitutes treason, as stipulated in Article 113 of the Criminal Code," Pansak said of the coup.

Students and academicians - who are part of the movement - have also been detained and later released by the security forces during the demonstrations.

"We have always warned this group of students and meted out punishments from light to heavy. But they repeatedly commit violations despite the fact that officers gave them a chance and regard them as the future of the country. We tried to warn them gently several times but they did not quit," senior government official Lieutenant Pitakphol Choosri told reporters.

Scores of police officers have also been deployed in Bangkok to prevent any untoward incident.