The world’s largest cryptocurrency fell as much as 6.3% to $20,715.69, its lowest since December 2020.
Bitcoin has lost around 28% since Friday and more than half of its value this year.
Smaller cryptocurrencies, which tend to move in tandem with bitcoin, also fell.
Ether, the second-largest token, fell as much as 9.4% to $1,090.
The token has tumbled after U.S. crypto lender Celsius this week froze withdrawals and transfers between accounts, stoking fears of wider fall-out in the digital asset market.