JP Morgan boss Jamie Dimon has warned that tighter government regulation on cryptocurrencies is imminent.
Speaking to CNBC yesterday, Dimon said that authorities currently view cryptocurrencies such as Bitcoin and Ethereum as "a novelty".
His comments follow a slump in Bitcoin's value earlier this month after he slammed cryptocurrencies as a "fraud".
Undeterred by accusations that his statements amounted to market abuse, Dimon has now said that the current craze for initial coin offerings (ICOs) "will end badly".
"Right now these crypto things are kind of a novelty," he said. "People think they're kind of neat. But the bigger they get, the more governments are going to close them down."
He clarified during the interview that he was not "upset about technology", supporting using blockchain to create digital versions of existing technologies.
The problem, he said, comes when currencies are "created out of thin air without government backing".
Bitcoin was trading up 3.55 per cent against the dollar today at $3,731.
The cryptocurrency smashed through the $5,000 barrier at the beginning of this month. But it has suffered a number of falls over the past few weeks due to both Dimon's criticism and increased regulation in China.