Hundreds of companies offering bitcoin and other cryptocurrencies are operating under the radar of UK regulators.
The Financial Conduct Authority (FCA) has issued 30 warnings this year about firms that are selling crypto. It issued 23 in December.
The surging value of crypto assets has spawned a multibillion-pound industry that is enticing savers with adverts on social media, at football grounds and on public transport. New firms are starting almost every day, causing a headache for regulators.
Celebrities are also fuelling the surge in interest. Crypto.com, one of the largest cryptocurrency exchanges, has an advert featuring Matt Damon, the Hollywood actor. Gwyneth Paltrow also endorses crypto investment and recently urged her 2.7 million followers on Twitter to give bitcoin to their loved ones.