The Police Commission decided unanimously on Friday that Thaksin Shinawatra should be stripped of his lieutenant-colonel rank.
The recommendation will be sent to police chief Somyot Poompanmoung today. If he agrees with it, the recommendation will be forward to the Prime Minister's Secretariat Office for action.
Pol Gen Chaiya Siri-ampankul, chairman of the panel considering the case, said on Friday panel members found Thaksin, being a suspect in a criminal case and then fleeing, had met one of the seven conditions for the penalty under the police regulation on rank stripping.
Pol Gen Chaiya insisted the panel members were not bullying anyone but simply acted by law. "The accused can explain in writing to the National Police Bureau."
The panel based its decision on the ruling by the Supreme Court's Criminal Division for Holders of Political Positions.
In 2008, Thaksin was sentenced in absentia to two years in jail by the court for abuse of power in the sale of state land to his then wife in an auction when he was prime minister. He fled Thailand before he was sentenced and has since lived in self-exile abroad.
Also on Friday afternoon, the Office of the Attorney General (OAG) said its had received a case against Thaksin from the police Technology Crime Suppression Division.
OAG spokesman Wanchai Rujjanawong confirmed the case involved Thaksin's interview with media in Korea, which authorities found detrimental to national security and the palace.
Since the act was committed abroad, attorney-general Trakul Vinitchaipak will decide how to proceed, Mr Wanchai said.
Thai media reported on Thursday the Royal Thai Army, via commander-in-chief Gen Udomdej Sitabutr, filed complaints against Thaksin on May 26 for breaking Sections 112, 326 and 328 of the Criminal Code.
Prime Minister Prayut Chan-o-cha also said later that day a lot of other people had filed similar complaints with police.
Section 112 provides: "Whoever, defames, insults or threatens the King, the Queen, the Heir-apparent or the Regent, shall be punished with imprisonment of 3-15 years".
Sections 326 and 328 involve defamation, with imprisonment not exceeding two years and a fine not exceeding 20,000 baht.
The former prime minister told Choson Media in Seoul last Wednesday some groups were behind the May 22, 2014 coup.