The Premier League are already investigating alleged financial breaches, regarding secret payments made by Chelsea to offshore companies.
Todd Boehly's consortium discovered the payments when they were in the process of purchasing the club from Abramovich and subsequently reported the anomalies to the Football Association, Premier League and UEFA.
A recent report claimed the Premier League were looking at Willian and Samuel Eto'o's transfers from Anzhi Makhachkala in August 2013.
Financial records allegedly show that payments, separate from any transfer fee, were made to "Russian entities".
The Football Association are also believed to be investigating the club, while UEFA have already issued a £8.6m fine, but any further scrutiny will be limited because Europan football's governing body can only focus on evidence from the last three years.
Now following an investigation by The Guardian and the Bureau of Investigative Journalism, further secret payments have come to light.
Leaked documents reportedly show a number of payments worth tens of millions of pounds delivered through offshore entities owned by Abramovich.
The secret transactions raise questions about whether Chelsea breached any rules, including Financial Fair Play regulations.
There is a risk that the investigation could result in punishments being handed out to Chelsea, such as a points deduction.
Possible beneficiaries are the agent of former Chelsea attacker Eden Hazard, an associate of ex-Chelsea boss Antonio Conte and several other individuals linked with the club.
Abramovich, who bought Chelsea in 2003, oversaw the most successful period in Chelsea's history before he was forced to sell the club in 2022 after being placed under sanctions due to Russia's invasion of Ukraine.
Under his ownership, the Blues won five Premier League titles, five FA Cups, three EFL Cups, two Champions League trophies, two Europa League titles, a UEFA Super Cup and one Club World Cup.