Watana Muangsook, a leading Pheu Thai Party member, reported to Bangkok South Criminal Court on Thursday morning after being released by the military late on Wednesday night.
Before being released he was taken to Nang Lerng police station where he was charged with violating the Computer Crime Act of 2007.
Mr Watana reported to the court and applied for bail, posting 100,000 baht as collateral.
He was accompanied by Kittiratt Na Ranong, acting Pheu Thai deputy leader and former finance minister, and Phumtham Wechayachai, acting Pheu Thai secretary-general.
During the proceedings, police sought permission from the court to detain him for 12 days, from March 3 to 14, while six or seven witnesses were questioned.
The court approved the police request.
Mr Watana then filed a request for bail, posting 100,000 baht as collateral.
The court later released Mr Watana on bail, with the condition he must not travel out of the country without court permission.
Mr Watana is required to report to the court again on March 14.
National Council for Peace and Order spokesman Col Piyapong Klinphan said Mr Watana was invited to fine-tune his attitude because he was found to have expressed opinions in a way which could affect the NCPO's work.
He said the intention was to ask for his understanding and cooperation, for peace and order.