Ross Barkley's transfer from Everton to Chelsea has been referred to police to investigate whether any "fraud" may have taken place, BBC News have reported.
This follows a report in the Times which revealed that Chelsea paid agent fees of £7m in addition to the £15m transfer fee.
The size of the agent fee in relation to the total of the transfer itself has raised eyebrows, as has the seemingly low cost of the deal.
Thank you to everyone for the well wishes and messages of support 💯 it’s an amazing feeling to have signed for Chelsea and I’m excited about the future at Stamford Bridge 🔵 Chelsea are a massive club with brilliant fans and I’m looking forward to working hard here and showing everyone what I know I’m capable of in the coming years ⚽ Despite a challenging few months I’ve loved every minute of my time at Everton and would like to thank everyone at the club, coaches, players and members of staff I’ve worked with for everything you’ve done for me over the past 13 years. I will always look back with fond memories of my time at Goodison Park and playing for my hometown club in front of my own people has been a huge honour for me. Everton will always have a special place in my heart 💙 I’m now looking forward to a new start and new chapter in my life at Chelsea and can’t wait to get going!
(You may also be interested in Everton's Brief Statement Following Ross Barkley's Chelsea Move Has Twitter in Stitches)
Mayor of Liverpool Joe Anderson - a lifelong Everton fan - has written to the FA, claiming that the deal "warrants serious investigation".
Barkley was believed to have been set to join Chelsea in the summer for £35m, but pulled out of the deal at the last minute. The agent fees agreed in the summer were not disclosed to the public due to the deal falling through.
I will be writing to .@premierleague & .@FA calling for investigation into the circumstances around the transfer of Ross Barkley between Everton and Chelsea. Agent pulls transfer on deadline day of £35 million doesn’t play again transfer 4 months later £20 million— Joe Anderson (@mayor_anderson) January 5, 2018
Agent fees have been called into question previously, most notably when Paul Pogba's agent - Mino Raiola - received £41m after the French midfielder's then world-record move to Manchester United.
The £7m paid to Barkley's agent pales in comparison to many others, although - at close to half of the transfer fee paid to Everton - it has led to concerns.
The FA's guidance is that agent fees should comprise no more than 3 per cent of the value of the transfer, but clubs and intermediaries are free to come to any arrangement that they wish.
In his letter, Mr Anderson tells FA chairman Greg Clarke and Premier League executive chairman Richard Scudamore that he feels "it is right that the public receive an assurance on this matter".
Barkley has yet to feature in the Premier League this season due to a hamstring injury.