Thailand’s king has reduced the prison term of former prime minister Thaksin Shinawatra from eight years to one year following the divisive politician’s return from 15 years of self-imposed exile.

The decision by King Maha Vajiralongkorn was published in the Royal Gazette, making it effective immediately.

Thaksin was prime minister from 2001 to 2006, when he was ousted by a military coup.

He fled Thailand in 2008 when he faced prison time on charges he described as politically motivated.

Thaksin returned to Thailand last week and was immediately sent to prison, but was quickly transferred to a state hospital because of what was described as his frail health.

It is widely believed that Thaksin, 74, returned home in the hope that a new government friendly to him would reduce his sentence, and that he may have made a deal with authorities.

Hours after Thaksin’s return, Srettha Thavisin of the Thaksin-affiliated Pheu Thai party won enough votes in parliament to become prime minister, ending more than three months of uncertainty after national elections in May.

Pheu Thai was able to cobble together a majority by forming a coalition with pro-military parties linked to a 2014 coup that ousted a government formed by Thaksin’s sister, Yingluck Shinawatra.

The decree granting Thaksin royal clemency said he had acknowledged his guilt. It said Thaksin had worked to benefit the country and was loyal to the monarchy, and could use his knowledge and abilities to help the nation and its people.

Prison officials said Thaksin had high blood pressure and low oxygen, could not sleep well and felt tightness in his chest.

Thai media reported that Thaksin can apply for parole after serving one-third of his sentence, or four months. They said he could remain in the hospital for that period with permission from the Correction Department’s chief.

Thaksin became prime minister in 2001 by promoting populist policies and using his telecommunications fortune to build his own political party, and was easily re-elected in 2005.

Thailand’s traditional royalist ruling class felt threatened by Thaksin’s popularity. His removal set off years of sometimes violent confrontations between his supporters and opponents.

Political parties with his backing continued to win elections but were forced from power several times by the courts and the army, both bulwarks of royalism.

Deputy prime minister Wissanu Krea-ngam, who is also acting justice minister, dismissed speculation that Thaksin was being treated with special leniency.

He said Thaksin will be treated as a normal convict and will be returned to prison to serve his term once his health issues are cleared up.

Mr Wissanu will soon lose his positions when Mr Srettha’s government takes office.