But many believe he has struck a deal that will keep him from serving more than a short period in prison, reports BBC.

Earlier in the day, he arrived in the country in a private jet.

Corrections Department officials delivered Thaksin to prison at 11.20am after he was taken to the Supreme Court to hear the court’s verdicts against him in three cases, reports The Nation.

According to reports, the court issued an eight-year detention order for him.

The court's criminal division for holders of political positions announced a statement saying Thaksin is convicted of 8-year imprisonment related to his three convictions passed on the 74-year-old in absentia.

The convictions include a two-year sentence for corruption in a lottery project, a three-year sentence for his involvement in an Export-Import Bank loan for Myanmar case, and a five-year sentence for his role in a mobile phone concession amendment case, reports Xinhua.

Thaksin was Thailand's premier from 2001 to 2006 but had been in self-exile abroad since 2008.

Thailand's parliament is due to vote later on Tuesday for a new prime minister as the Pheu Thai Party, which links to Thaksin, leads an effort to form the new government with former property businessman Srettha Thavisin as the prime minister candidate.