Owner Fawaz Al Hasawi has told the BBC he hopes the takeover of Nottingham Forest will happen in the next month.
The BBC also understands that Greek shipping magnate Evangelos Marinakis, who is accused of match-fixing and directing a criminal organisation in Greece, is the potential buyer.
Marinakis, who owns Olympiakos, denies the allegations as prosecutors decide whether he will face trial in Greece.
Al Hasawi says he is awaiting Football League clearance for the deal.
Forest have said they will not go into detail about potential investors.
It is understood that Kuwati businessman Al Hasawi, who purchased the Championship club in 2012, will remain as chairman and still own 20%.
Since last year, Marinakis has been facing allegations surrounding a match-fixing conspiracy involving Greek domestic games between 2011 and 2013.
Along with a number of Greek football officials and referees he has been accused of bribery and blackmail.
Marinakis is also alleged to have ordered the bombing of a bakery owned by a referee in 2012. He has also denied this.
Following a hearing in June 2015, the tycoon was obliged to pay €200,000 (£153,942) bail and banned from taking an active role with Olympiakos and in Greek football.
He has to report to police every 15 days until prosecutors decide if he will face trial in the coming months.
If the 48-year-old is found guilty of a charge of directing a criminal organisation he could face 10 years in prison, it is understood.
Marinakis has overseen Olympiakos wining the Greek Superleague six times since he bought the club in 2010.
Football League remains quiet
Marinakis is likely to pass the Football League’s “owners’ and directors’ test” – in place to “protect the image and integrity” of the league – as he has not been convicted of any crime.
The English Football League said it could not comment on individual cases as “matters relating to club takeovers are treated as private and confidential”.
The FA said it was a matter for the Football League and would not comment further.
Marinakis was cleared of a previous match-fixing allegation because of a lack of evidence.
Olympiakos have previously denied their president was linked to Nottingham Forest.
A spokesman for Nottingham Forest said the club would not give an “official response on potential individuals” looking to invest in the club.
“The club can assure all supporters that any potential investment will be carried out with the full approval from all relevant governing bodies required to ensure the best outcome for Nottingham Forest Football Club,” said a statement.
BBC East Midlands Today’s Natalie Jackson
“Fawaz Al Hasawi tells me he has put in £106m in his five years at Nottingham Forest.
He told me ‘I am waiting for a yes or a no from the Football League. All I need is the green light’.
“If the deal gets clearance from the Football League, Fawaz says he wants to remain as chairman and keep a small stake in the club and help Forest get back to the Premier League.”