Offices at Newcastle and West Ham have been raided as part of an investigation into suspected tax and National Insurance fraud, Sky sources understand.
HM Revenue and Customs officers were deployed at 6.30am on Wednesday in raids on the training ground and main offices of Newcastle United at St James' Park, and the London Stadium, home of West Ham.
HMRC officers carried out raids at West Ham's training ground in Rush Green, near Romford.
Staff at the London Stadium and West Ham's training ground were called this morning by the club and told not to come in - they have since been contacted and told they can now head into work.
A number of arrests were made related to £5m of suspected Income Tax and National Insurance fraud and Sky Sports News HQ understands that one of those was Newcastle's managing director Lee Charnley.
Newcastle's players were arriving at the club's training ground while the raids were ongoing, but despite the obvious shock continued with their normal daily duties as they prepared for Friday's clash with Cardiff City, which will be broadcast live on Sky Sports.
The raids are understood to be part of a wider HMRC investigation into the transfer of players between clubs in France and the UK.
It is thought their focus has been on remuneration in terms of image rights, benefits in kind and payments to agents, which may have defrauded the public purse.
A statement from HMRC read: "HMRC has arrested several men working within the professional football industry for a suspected Income Tax and National Insurance fraud.
"180 HMRC officers have been deployed across the UK and France today. Investigators have searched a number of premises in the north east and south east of England and arrested the men and also seized business records, financial records, computers and mobile phones.
"The French authorities are assisting the UK investigation, have made arrests and several locations have been searched in France.
"This criminal investigation sends a clear message that, whoever you are, if you commit tax fraud you can expect to face the consequences. As this is an ongoing investigation HMRC is unable to provide any further detail at this time."
A West Ham United spokesperson said, "The Club is cooperating fully with HMRC to assist their enquiries. No further comment will be made at this time."
Sky Sports News HQ also understands HMRC officials visited Chelsea's main offices at Stamford Bridge on Wednesday morning. However, there is no suggestion Chelsea are under investigation and nothing was confiscated. There is no allegation of wrongdoing made against anybody associated with Chelsea.
A Chelsea spokesman told SSN HQ: "In connection with its wider investigation, HMRC has requested certain information which the club will provide."