JP Morgan boss Jamie Dimon has said he would fire anyone trading bitcoin because it is "stupid" and "will blow up" - slamming the digital currency a day after the City watchdog sounded a warning of its own.

Bitcoin fell as low as $3,812 on Wednesday, according to CoinDesk, after Dimon's comments added to investor jitters over digital currencies. The value of bitcoin has soared this year, swelling from $1,000 in January.

“If we had a trader who traded bitcoin I’d fire him in a second for two reasons," he said. "One, it’s against our rules. Two, it’s stupid."

He added that it was "a fraud" and "worse than tulip bulbs," referring to the famous market bubble from the 1600s. "It won't end well. Someone is going to get killed."

Financial technology executives hit back at the comments, arguing that the rise of bitcoin was simply being viewed as a threat to big banks.

"Big institutions such as JP Morgan will need a plan if they are to avoid being a casualty of the financial revolution," said eToro co-founder Yoni Assia. "We shouldn't be surprised that this threat sparks extreme reactions from the industry's top insiders."

Mr Dimon's remarks came hours after the City watchdog warned investors that they should only take part in virtual currency fundraisings if they are prepared to lose all of their money.