Influential Thai ex-prime minister Thaksin Shinawatra landed in Bangkok on Monday, live TV images showed, ahead of a scheduled watershed ruling by the kingdom's top court which may see him jailed.

Thaksin jetted away last week as his family's party was ousted from office, fuelling speculation he had absconded from a Supreme Court inquiry probing whether he properly served a prison sentence.

But TV images showed him arriving back at Bangkok's Don Mueang Airport.

Thaksin, a billionaire who has loomed large over Thai politics for a quarter of a century, could be jailed if judges decide that the time he spent in hospital detention in 2023 instead of prison should not count as time served.

He spent only a few hours in jail before being transferred to a VIP wing of a hospital on medical grounds in 2023 upon his return from 15 years of self-exile to serve his sentence for conflicts of interest and abuse of power.

Thaksin was sentenced to eight years for abuse of power and conflicts of interest, which was commuted to a year by the king.

He was released on parole after six months in detention. (AFP/Reuters)