Bitcoin fell by 8.9% to $34,156 at 1000 GMT on Sunday, losing $3,344.54 from its previous close.
Bitcoin, the world’s biggest and best-known cryptocurrency, is down 47.4% from this year’s peak of $64,895.22 on April 14.
Ether, the coin linked to the ethereum blockchain network, dropped 11.5% to $2,031.96 on Sunday, down $264.35 from its previous close.
A rebound in bitcoin held strong on Thursday, even as the US Treasury Department called for new rules that would require large cryptocurrency transfers to be reported to the Internal Revenue Service and the Federal Reserve flagged the risks cryptocurrencies posed to financial stability.
The comments from US officials came one day after a brutal sell-off on concerns over tighter regulation in China and unease over the extent of leveraged positions among investors sank the world's biggest cryptocurrency to its lowest level since late January.
Earlier, Bitcoin slumped after the Tesla Inc chief announced in May that Tesla would no longer accept bitcoin for car purchases, citing long-brewing environmental concerns for a swift reversal in the company's position on the cryptocurrency.