Newcastle and West Ham's grounds have been raided by Her Majesty's Revenue and Customs after an investigation into the clubs' transfer dealings.
A stratement from HMRC has revealed a number of arrests have been made as part of a probe into suspected tax and national insurance fraud.
Business records, financial records, computers and mobile phones have been seized in numerous offices, including those at St Jams' Park and the London Stadium.
Newcastle managing director Lee Charnley is understood to have been one of a number of people arrested.
“HMRC has arrested several men working within the professional football industry for a suspected Income Tax and National Insurance fraud," read the statement.