A director of operator 666Bet has been arrested in connection with a Â£21m money laundering and fraud investigation.
Paul Bell was arrested at Heathrow Airport last week along with six others as part of Operation Bannock, an investigation led by HMRC.
Bell was later released before being re-arrested the following day on the Isle of Man.
Thirteen properties have been raided and Â£1m in cash has been seized as part of the investigation, which has not been linked to 666Bet.
The UK Gambling Commission and the Alderney Gambling Control Commission earlier this month suspended the licences of 666Bet, which are held by Metro Play Limited, its online casino subsidiary brand.
666Bet head of sportsbook and brand Neil Andrews wrote in an email to the Independent on Sunday: âI can categorically state the investigation does not relate to 666Betâs activities in the gaming world.â
666Bet launched last year, signing sponsorship deals with football clubs West Bromwich Albion, Leicester City and Leyton Orient, which terminated its deal with the operator following the suspension of the licences.
Former Tottenham Hotspur manager Harry Redknapp, who appeared in 666Bet's television adverts, told the Independent on Sunday: âI just did an advert for them. I don't know anything about it at all. Not a clue.â
A source told the Independent on Sunday that Bell denies the allegations.