A wave of apparently arbitrary detentions by Thailand's military leaders following last month's coup is drawing the ire of top human rights groups.
The military junta led by General Prayuth Chan-ocha has arrested more than 200 politicians, journalists and activists since seizing power May 22.
Many have since been released, but others remain jailed in undisclosed locations and have not been allowed to see their families or lawyers.
Human Rights Watch on Wednesday urged the junta to stop carrying out arbitrary arrests and detentions, "including apparent forced disappearances."
The group said it was particularly concerned about 27-year-old Red Shirt activist Kritsuda Khunasen, who was arrested by soldiers on May 28.
It said Kritsuda's detention has already exceeded the seven-day administrative detention period permitted under the martial law invoked by the military.
Asia Director Brad Adams said the military's failure to disclose where they are holding activists such as Kritsuda "heightens concerns for their safety."
Last week, Amnesty International also condemned what it called the "systematic and widening crackdown on key human rights" by Thailand’s military.
In statement, the London-based group said the army's course of action in arresting critics "is looking increasingly like a purge."
It also criticized the Thai military for "enforcing widespread censorship of the media" since taking power.
The military says the coup was necessary in order to stop political protests and unrest that had killed nearly 30 people in the past seven months.
Junta officials have said they have no plans to remain in power for the long-term, but say they must create conditions for elections before stepping down.
Thailand's military has staged 12 coups in the last 80 years.