BANGKOK, Aug 31 (Reuters) - Thailand's billionaire former premier Thaksin Shinawatra has submitted a request for a royal pardon, local media reported on Thursday, citing the outgoing justice minister.

The influential Thaksin, Thailand's most famous politician, is currently serving an eight-year prison sentence for abuse of power and conflicts of interest after returning from 15 years of self-imposed exile last week.

A representative of the 74-year-old Thaksin declined to comment when asked by Reuters for confirmation. His lawyer on Wednesday said Thaksin was preparing the request on his own.

The former telecoms tycoon returned to Thailand last week in a dramatic homecoming, arriving on a private jet and greeting supporters before being moved to a prison. On his first in jail, he was transferred to a police hospital, with authorities citing chest pains and high blood pressure.

The pardon request was submitted Thaksin's family, Justice Minister Wissanu Krea-ngam was quoted as saying in local media reports.

A request for royal pardon must be submitted through the corrections department to the justice minister. It is then considered by the prime minister, who must then submit it to King Maha Vajiralongkorn.

Thaksin's return last week coincided with political ally and fellow tycoon Srettha Thavisin winning a parliamentary vote to become prime minister that same day, with pro-military parties backing his Pheu Thai Party, founded by the Shinawatra family.

The events added to speculation that Thaksin has struck a deal with his bitter rivals in the conservative establishment and royalist military, which ousted him in a 2006 coup, accusing him of corruption and disloyalty to the powerful monarchy.

Thaksin denied those allegations and has rejected talk of a deal with the generals.