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.
HM Customs and Revenue refused to name any of the people held in the raids but said that 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.