One of the most influential figures in the European fintech industry has added his voice to calls for higher standards in the growing market for fundraisings backed by cryptocurrencies.

Oliver Bussmann, president of Crypto Valley Association, a not-for-profit association supporting the development of blockchain technology, said: "There are ICOs [initial coin offerings] out there that I wouldn't subscribe to. We need to find a way to make it sustainable. End investors need to be protected."