LONDON (Reuters) -Britain is to restrict consumers' use of credit cards to buy crypto and their access to crypto lending products, the regulator said on Friday, a move aimed at improving protection as cryptoassets are regulated for the first time. The finance ministry this week said it would bring cryptocurrencies under compulsory regulation, with exchanges, dealers and issuers all coming under the existing rulebook. Crypto trading has exploded in popularity, with around 7 million people - about 12% of the adult population - owning cryptoassets, but it remains largely unregulated, the Financial Conduct Authority (FCA) said.