Newcastle United managing director Lee Charnley has been arrested and the club is under investigation by HM Revenue and Customs over their transfer dealings.
West Ham have also been targeted as part of a probe into 'suspected income tax & national insurance fraud', according to HMRC.
Charnley became managing director at Newcastle in April 2014 and it was recently revealed that the club forked out more than £10million in agents' fees for the 2016/17 season, twice the figure paid out by their closest rivals, Aston Villa.
Newcastle sealed promotion to the Premier League on Monday with a 4-1 win over Preston at St.