The biggest cryptocurrency fell to $9828.89 by around 1630 GMT after David Marcus, the company's top executive overseeing the planned Libra project, answered questions from the Senate Banking Committee. Earlier in the day, bitcoin had lost around 3pc.

Traders said the trigger for the selling was not immediately clear. During the testimony, a US senator said Facebook was "delusional" to believe people will trust it with their money as the social media giant fights to get Washington onside for its planned Libra project, aimed for launch in 2020.