Mark Carney faces calls to come clean about a secret meeting with Facebook's founder over plans for a new digital currency.

The Bank of England governor met Mark Zuckerberg this year to discuss the controversial idea and has since declared he will keep 'an open mind' about it.

But concerns about the currency, called Libra, have prompted MPs and experts to call on the Bank to give details of the pair's discussion.

Mark Carney faces calls to come clean about a secret meeting with Facebook's founder over plans for a new digital currency

Facebook plans to test Libra in some countries in coming months before launching it around the world in 2020.

It will allow customers to pay for products without leaving its website or smartphone apps. But critics say the currency presents yet another risk for Facebook users after a string of privacy scandals at the tech firm.

There are also fears Libra could be used to launder money or finance terrorism. Last night Sir Vince Cable, a former business secretary and leader of the Liberal Democrats said: 'I regard Mark Carney as a good governor, but I hope he will speak about this meeting publicly because this idea does seem to me to be a potentially dangerous one, particularly when central banks are already struggling to maintain financial stability.

Facebook plans to test Libra in some countries in coming months before launching it around the world in 2020

'Mark Zuckerberg should focus on managing his business properly, rather than embarking on a proposal that is fraught with so much risk.'

French finance minister Bruno Le Maire said it was 'out of the question' that Libra could be a fully-fledged currency.

And Germany's Markus Ferber, on the European Parliament's committee on economic and monetary affairs, said Facebook could become a 'shadow bank'.

A Bank of England spokesman refused to comment on what Carney and Zuckerberg discussed.