BANGKOK, Sept 10, 2025 (BSS/AFP) - Thailand's influential ex-prime minister Thaksin Shinawatra began his first full day in prison Wednesday after a court ruled that he had improperly served a previous jail term in hospital.

Shinawatra's political clan has for two decades been the key foe of Thailand's pro-military, pro-royalty elite who view their populist brand as a threat to traditional social order.

The dynasty's momentum is flagging after a litany of legal and political setbacks, culminating in his daughter Paetongtarn Shinawatra being ousted last month from the prime minister's office.

Tuesday's Supreme Court ruling deals one of the most painful blows yet to Thailand's biggest political heavyweight, as judges ordered the 76-year-old's transfer to Bangkok Remand Prison.

He was later that day transferred to Klong Prem prison where he is expected to serve the rest of his one-year term, according to a statement from the corrections department.

The department offered no further updates on Wednesday regarding Thaksin's case.

Thaksin was elected prime minister in 2001 and again in 2005, and took himself into exile after his second term was cut short by a military coup.

After returning in August 2023 he was sentenced to eight years for corruption and abuse of power.

But he never spent a night in a cell -- whisked to a private hospital room, his sentence was reduced to one year by royal pardon, before he was freed in an early release scheme for elderly prisoners.

The timing of his return and his medical transfer, which coincided with his Pheu Thai party forming a new government, had fuelled public suspicion of a backroom deal and allegations of special treatment.

The Supreme Court on Tuesday ruled that that the enforcement of his prison sentence was unlawful and that he had not been suffering from a critical emergency condition.