Suthep, leader of the People's Democratic Reform Committee (PDRC), along with four members of the organisation after their release, were taken to the office of the attorney general where they would face insurrection charges, the Bangkok Post reported.
Former prime minister Yingluck Shinawatra was released Sunday night from detention.
Thai Army Commander-in-Chief Gen Prayuth Chan-ocha detained more than 41 officials after he declared a coup Thursday. The officials were questioned at the army auditorium and army barracks and then detained at "safe houses".
Prayuth also dissolved the Senate Saturday and took over the authority of the House of Representatives and the Senate for the time being in case any actions require approval of the parliament. He has also declared himself to be the temporary prime minister for administrative purposes.
It is the 12th military coup in Thailand since the end of absolute monarchy in 1932.
Prayuth Tuesday declared martial rule in the country and called on the public not to panic, saying that the military would maintain peace and order and bring the situation back to normal.