Srisuwan Janya, secretary-general of the Association of Organisations Protecting the Thai Constitution, has been invited by the military for talks to "promote understanding" after he sought an ethics investigation against Prime Minister Prayut Chan-o-cha and Deputy Prime Minister Wissanu Krea-ngam.
Mr Srisuwan on Thursday afternoon posted on the social media a picture of soldiers, saying: "The soldiers are taking me to the 1st Army headquarters on Ratchadamnern Road."
Sources said it was the peace-keeping force of the 1st Army that invited Mr Srisuwan for talks because he earlier this week submitted a petition with the Office of the Ombudsman, asking it to conduct an ethics probe on Gen Prayut and Mr Wissanu.
He accused Gen Prayut of appointing a lot of military officers, both retirees and those in active duty, to the National Reform Steering Assembly.
He also accused Mr Wissanu of appointing his siblings to sit on the NRSA.
Mr Srisuwan said the NRSA was supposed to comprise people of all walks of life, not just close associates and relatives.