There was a big increase in complaints about cryptocurrency service providers in 2017/18, according to the Financial Ombudsman Service, with the most common issues failure to follow instructions, poor disclosure and inappropriate advice.

The FOS annual review says cryptocurrency disputes were generally about financial service provider terms and conditions, and included some contract for difference disputes in which two parties agree that one will pay the other the difference between the current value of the underlying cryptocurrency and its value at contract time.

Disputes were also lodged about pricing and transactions. These included disputes where the price of a particular cryptocurrency provided was different to the price available elsewhere.

Many disputes concerned a failure by the financial service provider to act on a request from the applicant to withdraw funds from their account in a timely manner.

Other issues involved stolen or hacked cryptocurrency holdings.

FOS lumps cryptocurrency disputes together with hedging products, contracts for difference, futures, foreign currency transactions, options and swaps.

It recommends that investors thoroughly check the terms and conditions of service provider contracts before investing or transacting