Democrat leader Abhisit Vejjajiva has instructed the party's legal team to file a complaint against red-shirt leader Wuthipong Kochathamkhun, alias Ko Tee, accusing him of lese majeste, spokesman Chavanond Intarakomalyasut said on Wednesday.
Mr Chavanond said Mr Wuthipong made remarks deemed detrimental to the royal institution in an interview with foreign media, which could affect national security.
He said Mr Abhisit had instructed the party's legal team to submit a complaint asking caretaker Prime Minister Yingluck Shinawatra, Labour Minister Chalerm Yubamrung, as director of the Centre for the Administration of Peace and Order (Capo), and Department of Special Investigation (DSI) chief Tarit Pengdith to take legal action against Mr Wuthipong.
The legal team would also file a complaint against Ko Tee with the Crime Suppression Division and provincial police across the country.
On Thursday, Democrat deputy spokeswoman Mallika Boonmeetrakul would submit a letter to Gen Prayuth Chan-ocha, the army chief, asking that he take serious action against acts of lese majeste.