HMRC officers have raided the offices of soccer clubs Newcastle United and West Ham United as part of a fraud investigation.
The tax regulator told the BBC it had deployed a total of 180 officers to search a number of premises across the UK, with the French authorities assisting the investigation by examining locations in France.
A spokesman said this had resulted in the seizure of a number of business records and other financial documents.
The HMRC representative added that a number of men working in professional football had been arrested in relation to suspected National Insurance and income tax fraud.
West Ham's offices at London's Olympic Stadium were confirmed to have been raided by the BBC, as well as the offices of Newcastle United at St. James' Park.
The tax regulator told the broadcaster the investigation is ongoing, and no further detail could be provided.
In the case of Newcastle, the news comes just three days after the club secured promotion to the Premier League in front of their adoring fans at St James' Park.
West Ham, meanwhile, moved to the Olympic Stadium last summer and are firmly established in the Premier League.