Former Thai Prime Minister Thaksin Shinawatra greets his supporters after landing at Bangkok's Don Mueang airport on August 22, 2023. Lillian Suwanrumpha, AFP/file

Thailand's controversial former prime minister Thaksin Shinawatra has been granted a royal pardon, his lawyer said Saturday, a day after his daughter became the kingdom's new premier.

The 75-year-old billionaire is one of thousands granted amnesty by King Maha Vajiralongkorn in a gesture of clemency to mark his birthday.

Thaksin was jailed for eight years on graft and abuse of power charges dating back to his time in power when he returned to the kingdom almost a year ago after 15 years of self-exile.

But his sentence was cut to one year by the king and he was later released on parole because of his age and poor health.

The amnesty was announced in the official Royal Gazette, and Thaksin's lawyer Winyat Chatmontree said that the two-time premier benefitted.

"Thaksin Shinawatra is among those granted the royal pardon," he said on his personal Facebook account.

"He will later receive a document from the prison saying he is a free man."

The Royal Gazette published on Saturday said that "the king had given opportunities for those to improve themselves and benefit their country".

The pardon for prisoners with good conduct came almost a month after King Vajiralongkorn celebrated his 72th birthday in late July.

The ex-PM was originally set to complete his one-year parole on August 31.

Lawmakers approved on Friday Thaksin's daughter Paetongtarn Shinawatra as premier.

At 37, she is the kingdom's youngest prime minister and the third Shinawatra to hold the job after her father and aunt Yingluck -- both of whom were ousted in military coups.

Paetongtarn's elevation to the top job came about after the kingdom's Constitutional Court sacked previous premier Srettha Thavisin for appointing a cabinet minister with a criminal conviction.