Bitcoin has slumped around 30pc from 18-month highs of nearly $14,000 touched after Facebook's move, following a growing chorus of concern among regulators and politicians from the United States to Europe at the social media giant's plans.

And the so-called altcoins have fared even worse.

The second-biggest coin Ethereum has slumped by nearly half. The third largest, Ripple's XRP, is down by around 40pc, while Litecoin and Bitcoin Cash have slumped by 40pc and 42pc respectively.

On Wednesday, G7 finance chiefs cast a cloud over prospects for Facebook's Libra digital coin, insisting tough regulatory problems would have to be worked out first.

The Bank of Japan governor said a G7 task force looking at cryptocurrencies like Libra would likely grow to include a broader range of regulators beyond the bloc.

Facebook faced in the US more questioning by lawmakers after a bruising first bout on Tuesday, when senators from both parties condemned the project.

Where bitcoin goes, altcoins tend to follow.

Price moves for smaller coins have been closely correlated with their bigger cousin through crypto's first decade, even as altcoins seek to gain prominence among investors and real-world usage.

After Facebook unveiled its Libra cryptocurrency, bitcoin soared as much as 55pc in just nine days as investors bet the social media giant's gambit would herald mass adoption of cryptocurrencies. The top four altcoins also soared, climbing between 10pc and 33pc.

"When things are going up bitcoin tends to outperform and when crypto goes down the altcoins tend to take larger losses," said Mati Greenspan, an analyst at eToro.