Newcastle United boss Lee Charnley has been arrested by officials investigating a suspected income tax and national insurance fraud.
The managing director of the newly-promoted club was one of several men held during raids by tax authorities in the UK and France, a source confirmed.
It has been widely reported that both St James's Park has been raided as part of the probe.
HM Customs and Revenue refused to name any of the people held in the raids and declined to comment on reports that West Ham United were also involved in the probe, but said premises in the North East and South East of England had been raided, as well as locations in France.
Business and financial records, computers and mobile phones were also seized in the raids.
In a statement, the service said: "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."
Newcastle United were promoted back to the Premier League earlier this week at the first time of trying.
Charnley, 39, who became boss of the Mike Ashley-owned club three years ago, has been credited for keeping manager Rafa Benitez despite last season's relegation from the Premier League.
Meanwhile, a West Ham spokesman confirmed the club's offices at the London Stadium were raided by HMRC officers.
They said: "The club is cooperating fully with HMRC to assist their enquiries.
No further comment will be made at this time."