Chelsea owner Roman Abramovich held secret investments in footballers not owned by his club, an investigation has discovered.
The players included the Peruvian winger Andre Carrillo, who turned out against Chelsea in Champions League matches in 2014.
He held rights in the players through a company based in the British Virgin Islands.
Mr Abramovich’s spokeswoman stressed no rules or regulations were broken.
But former Football Association chairman Lord Triesman has questioned whether it was “proper” for the owner of a football club to have an interest in players in other teams.
A leak of documents – banks’ “suspicious activity reports” – that have been called the FinCEN Files and seen by BBC Panorama has revealed that Mr Abramovich is behind an offshore company called Leiston Holdings.
Leiston was taking stakes in footballers overseas through third-party ownership (TPO).
This is where investors buy a share of a footballer’s future transfer value from cash-strapped clubs.
The practice was banned in the English Premier League in 2008 but not internationally until 2015.
Chelsea faced Sporting Lisbon in the Champions League group stage in 2014.
And Carrillo lined up for Sporting in both matches.
So in Lisbon in September and Stamford Bridge in December, Mr Abramovich had an interest in 12 players on the pitch.
Lord Triesman told Panorama: “I don’t think it can possibly be proper for the owner of a football club to own players in other football clubs. That is precisely why third-party ownership is banned.”
“It casts suspicion and a shadow right across football. On the documents I’ve seen I would’ve wanted, as chairman of the FA, to investigate them.”
It comes as Mr Abramovich appears to be making heavy investments in Chelsea again this year.