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.
Twelve players on the pitch
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.