JP Morgan Chase chief executive Jamie Dimon doubled down on his past criticisms of bitcoin today, declaring it a "fraud" and saying he would fire any trader known to be trading the cryptocurrency.

Dimon gave the remarks during an appearance at an event hosted by Barclays, according to reports from Bloomberg and CNBC. A long-time critic of bitcoin – he said that the cryptocurrency would "not survive" back in November 2015 when the price was fluctuating around the $400 level.

Dimon aimed his remarks at the activity in the world's cryptocurrency markets and echoed those who've said that they're in bubble territory.

He was quoted as saying:

Dimon later added that the cryptocurrency "will blow up," according to CNBC. It was also during that appearance that said that he would terminate any trader that he found to be trading bitcoin for being "stupid."

In the wake of his speech, some observers, including Bloomberg, noted that bitcoin prices started to fall after Dimon's remarks. Other factors likely shaping the market today are continued fears that China will move to close domestic cryptocurrency exchanges, a state of affairs that has already led at least one trading platform to freeze its operations.

Bitcoin prices are currently at $4,077.82, down more than 2% for the day, according to the CoinDesk Bitcoin Price Index (BPI).

Jamie Dimon image via Wikimedia