A leading human rights group has written to the Premier League to challenge Thaksin Shinawatra's right to own Manchester City.
Thaksin completed his purchase of Manchester City earlier this month
Human Rights Watch (HRW) claims Thaksin is "a human rights abuser of the worst kind" and should not have passed the League's 'fit and proper person' test.
Thaksin, the Thai prime minister from 2001 to 2006, denies the allegations.
"Under any definition, I don't see how Thaksin can be fit and proper," HRW's Brad Adams told BBC Sport.
"I've written a letter to the Premier League asking what this test means."
Thaksin's lawyer, Noppadol Pattama, told BBC Sport that the allegations were completely unfounded.
"The civil and human rights charges against him have never been proven," said Noppadol.
"My client deserves to be treated as an innocent man, until proven guilty.
"So far there hasn't been any solid evidence against him."
The Premier League has replied to the letter and issued a statement defending the fit and proper person test.
"We have very clear rules on the ownership of our clubs," the statement read.
"These rules go above and beyond any requirement by company law and are some of the sternest in any UK industry."
Amnesty International shares many of HRW's concerns and their spokesperson told BBC Sport: "Thaksin did preside over some very serious human rights violations.
"If the Premier League wants to take any of that into account when making their decisions, we're happy to make our documents available to them."
The allegations against Thaksin are that, during his time as Thai prime minister, he:
Presided over extrajudicial killings during the notorious "war on drugs". HRW says 2,500 people were killed during one three-month period at the start of 2003.
Told the Thai military to employ any means to suppress an insurgency in the south of Thailand.
Suppressed the Thai media.
Thaksin's lawyer, Noppadol, countered: "As far as I am concerned, he (Thaksin) has never instructed any public officer to execute a drug dealer.
We will be able to prove his innocence after the general election when we are sure our client will get a fair trial
"We just tried to solve the drug problem in Thailand by getting tough with criminals. But he has never issued any instructions for shoot-to-kill policies.
"I hope Manchester City fans and British people are fair-minded. They should suspend their judgement before deciding Thaksin is not fit. He is a fit and proper man to run the club."
Prospective owners must pass a "fit and proper person test" before buying a Premier League football club.
This is basically a list of offences, which the prospective owner must not have been convicted of.
Thaksin passed this before completing his buy-out of City earlier this month.
The former Thai Prime Minister faces charges of conflict of interest and dereliction of duty following a land deal conducted by his wife, Pojamarn, in 2003.
If convicted, the Thai government could request his extradition from Britain.
However, this would almost certainly not be granted, because the request would probably be seen as being politically motivated.
Thailand is ruled by a military-installed government that assumed power by overthrowing Thaksin in a coup in 2006.
Yet the situation could change if a democratically-elected government made the request - and elections are scheduled for December this year in Thailand.
Noppadol said he was sure his client would be acquitted if a democratic government assumed power in Thailand.
"We will be able to prove his innocence after the general election when we are sure our client will get a fair trial," he told BBC Sport.