Chelsea are yet to pay up to £71m of the £97.5m fee they agreed with Inter to re-sign Romelu Lukaku last summer.
The Blues moved to bring Lukaku back to Stamford Bridge after an eight-year absence following an impressive two seasons in Italy, helping Inter topple Juventus at the top of Serie A to win the Nerazzurri's first Scudetto in over a decade.
But it hasn't quite worked out for Lukaku back at his boyhood club just yet, registering just five Premier League goals and often being overlooked up top to Kai Havertz.
The Sun report that amid Chelsea's need to sell the club after sanctions were brought against Roman Abramovich, the Blues still need to pay up to £71m for the Belgium striker, though not directly to Inter.
They also owe around £100m in transfer fees for players in their current squad, though they are in line to receive £167m from other clubs regarding past player sales.
Chelsea are currently operating on a special licence following the UK government's decision to sanction Abramovich, one of which is the introduction of what is effectively a transfer embargo. However, they are still able to pay and receive fees for transfers that have already been completed, with the only issue being whether they have the resources to pay other clubs what they owe them.
In regards to the Lukaku deal, Chelsea paid Inter an initial instalment of £19m - a figure disclosed by the Italian side when they refinanced their debts earlier this year - and would pay them a further four instalments over the course of the season.
In an attempt to raise funds, Inter made a deal with a financial institution, and so the remaining instalments for the Blues will go to this third party instead of the San Siro club.
Source : 90min