Former Prime Minister Thaksin Shinawatra was formally indicted on Tuesday on a charge of insulting Thailand's monarchy, prosecutors announced at a news conference.
Thaksin reported himself to prosecutors just before 9 a.m. local time (0200 GMT) and the indictment process had been completed, Prayuth Bejraguna, a spokesperson for the Office of the Attorney General, said.
Despite being ousted from power 18 years ago, Thaksin remains an influential figure in Thai politics, as does the Pheu Thai Party tied to him. He only recently returned to Thailand after years abroad.
The comments in question stem from a 2015 interview, shortly before the death of Thailand's previous King Bhumibol Abdulyadej and soon before his son Maha Vajiralongkorn took the throne.
Thailand is one of a few remaining countries to still impose jail sentences for perceived insults or defamation of royalty. Each count can carry a maximum sentence of 15 years.
msh/jsi (AP, Reuters)