Sky Vegas sent the “Bet £5 get 100 free spins” offer to 41,395 customers who had self-excluded and 249,159 customers who had unsubscribed from emails, The Guardian reports.

Flutter UK and Ireland, which owns Sky Vegas, apologised for the email, which it said was sent in error.

Andrew Rhodes, chief executive of the Gambling Commission, said: “Self-excluded customers are likely to be suffering gambling harm and should absolutely not be sent direct marketing that could tempt them back into gambling.

“We would advise all operators to learn from Sky Betting & Gaming’s costly errors and ensure their systems are robust enough to always prevent the self-excluded, and those who have clearly rejected marketing, from receiving promotional material.

“This latest fine would have been a lot higher had Sky Betting & Gaming allowed any of the self-excluded customers to actually gamble, failed to cooperate, and not taken decisive action aimed at preventing a repeat.”