Dutch gambling regulator Kansspelautoriteit (KSA) has imposed a €280,000 weekly penalty on Winbet for operating in the market without a local licence.
The penalty relates to four sites that Winbet operates: galaxyspins.com, winnercasino1.bet, superb1.bet and doctorspins.com.
The regulator imposed the penalty after finding that all of these sites allowed players in the Netherlands to create an account, make deposits and participate in unlicensed gambling.
Winbet does not currently implement any measures to prevent Dutch players from accessing its websites.
The regulator has warned the operator that if it does not withdraw from the Dutch market, it will face a penalty of €280,000 per week, up to a maximum penalty of €840,000.
The KSA said: “The Netherlands has a regulated gambling market to better protect players. The KSA therefore takes tough action against illegal supply.
“With an order subject to penalty, illegal supply is often quickly stopped. Providers can also be fined for the period in which the illegal supply was available.”