The Military Court on Monday approved a request from the Crime Suppression Division to further detain Pheu Thai Party key member Watana Muangsook.
The CSD told the court that an investigation into the case involving the former commerce minister was still under way and another 12-day detention was necessary.
Mr Watana is charged with ignoring a ban on political activity. The charge was filed to the CSD by the National Council for Peace and Order on April 21. The first 12-day detention ends on Monday.
The staunch critic of the draft charter was released on bail and is ordered to report to court on the day that the detention period ends. He was sent to a military camp at the 9th Infantry Division in Kanchanaburi last month after continuing to air his comments against the draft on his Facebook account.
Mr Watana is facing another charge on the Computer Crime Act filed by state prosecutors. He denies both charges.
