Mr Veera, a former coordinator of the Thai Patriots Network, and Gen Boonlert, chairman of the Pitak Siam group, reported to the NCPO before noon on Monday in response to a summons.
They were released about 3pm.
Gen Boonlert said in an interview with television reporters afterwards that Gen Paiboon Khumchaya, the assistant army chief and NCPO's chief of legal and justice affairs section, asked him and Mr Veera to let the NCPO know before conducting any activity which may be construed as violating the NCPO's orders including the ban on a political gatherings.
They agreed to comply with the request, Gen Boonlert said.
Gen Boonlert organised a reception for Mr Veera, who was recently released on a royal pardon from a Cambodian prison, at the Royal Turf Club on Sunday. This prompted the NCPO to issue an order for the two to report to it today.