More than 50 firms promoting cryptocurrencies have been hit with an enforcement notice by UK regulators in a “red alert” warning not to dupe consumers with false marketing.

With just months to go until tough new measures are likely to come into force, where rule-breakers could be prosecuted, fined, or even shut down, the Advertising Standards Authority told the businesses to review their advertisements' compliance as it prepares a crackdown on “misleading and irresponsible crypto ads”.