Facebook's plan to launch a global currency to serve the world's unbanked is already facing severe scrutiny over how it will be used, with European officials claiming it risks becoming a "shadow bank".

France's Finance Minister Bruno Le Maire called for central bank governors to make assurances that the new Libra cryptocurrency will face appropriate regulation to avoid it being used as a tool for money laundering and financing terrorists.

Speaking on Europe 1 radio, Mr Le Maire said it was "out of the question" that Libra be allowed to become a sovereign currency. "It can't and it must not happen," he said.

Other figures to raise concerns about Libra included Markus Feber, a German member of the European Parliament, and Bank of England Governor Mark Carney.

"Anything that works in this world will become instantly systemic and will have to be subject to the highest standards of regulation," Mr Carney said at the European Central Bank's annual symposium in Sintra, Portugal.

Facebook birthday: 15 defining moments for the social network Show all 15 1 /15 Facebook birthday: 15 defining moments for the social network Facebook birthday: 15 defining moments for the social network Facebook is born On 4 Feb, 2004, 19-year-old Harvard student Mark Zuckerberg launched a website called 'TheFacebook' from his dorm. Within 24 hours the college social network had more than 1,000 users Wikimedia Commons Facebook birthday: 15 defining moments for the social network Winklevoss twins sue Zuckerberg Within one week of launching, fellow Harvard students Cameron Winklevoss, Tyler Winklevoss and Divya Narendra accused Zuckerberg of stealing their idea. It would be four years later when the resulting lawsuit was finally settled Facebook birthday: 15 defining moments for the social network Open for business The social network finally opened it platform to everyone on 26 September, 2006. The move proved the catalyst in supercharging the site's already explosive growth PA Facebook birthday: 15 defining moments for the social network Billion-dollar bid Yahoo offered $1 billion to buy Facebook in September 2006 but Zuckerberg turned it down. 'I don’t know what I could do with the money,' Zuckerberg reportedly said. 'I’d just start another social networking site' Reuters Facebook birthday: 15 defining moments for the social network In the money In September 2009, almost five years since the site launched, Facebook turned a profit for the first time Getty Images/iStockphoto Facebook birthday: 15 defining moments for the social network Taking the lead Facebook overtook MySpace in 2010 to become the world’s most popular social network Facebook birthday: 15 defining moments for the social network Taking on the tech giants In 2011, Google launched its own social network that it hoped would knock Facebook from its perch. Despite its initial success, Google+ ultimately failed and will be shut down completely in 2019 Getty Facebook birthday: 15 defining moments for the social network Facebook goes public On 18 May, 2012, Facebook went public. The initial public offering raised $16 billion – the third largest in US history Facebook birthday: 15 defining moments for the social network Gobbling up the competition Facebook acquired Instagram in April 2012 for $1 billion, consolidating its position as the world's leading social network Reuters Facebook birthday: 15 defining moments for the social network One billion users On 4 October, 2012, Zuckerberg announced that Facebook had hit 1 billion users. 'If you’re reading this: thank you for giving me and my little team the honour of serving you,' he wrote in a blog post Getty Images Facebook birthday: 15 defining moments for the social network Expanding its empire In February 2014 Facebook acquired the messaging app WhatsApp for $19.3 billion REUTERS/Dado Ruvic Facebook birthday: 15 defining moments for the social network Two billion users In June 2017, Facebook passed the 2 billion user milestone REUTERS/Dado Ruvic Facebook birthday: 15 defining moments for the social network Privacy scandal On 17 March 2018, news broke that UK firm Cambridge Analytica had harvested data from around 87 million Facebook users for the purpose of political profiling in the build up to the 2016 US presidential elections Shutterstock Facebook birthday: 15 defining moments for the social network Record profits Despite the scandals and subsequent #DeleteFacebook campaign, Facebook posted record profits just before its 15th anniversary, the equivalent of $7.37 from each of its 2.32 billions users iStock/Independent Facebook birthday: 15 defining moments for the social network Unhappy users A study found that people are happier when they don’t use Facebook, adding to mounting evidence surrounding the impact social media has on mental health Rex Features

With more than 2 billion users around the world, Mr Ferber added that financial regulators should work to ensure Facebook does not become a "shadow bank". He said companies "must not be allowed to operate in a regulatory nirvana when introducing virtual currencies".

The decentralised and semi-anonymous nature of the current crop of cryptocurrencies – led by bitcoin – mean they have previously been blamed for offering a way for criminal and terrorist organisations to transfer funds across borders.

A 2015 report by web-intelligence firm S2T found that Isis was using bitcoin for fundraising and supporting US-based terror cells.

Facebook's new cryptocurrency is backed by 27 other companies – including PayPal, Mastercard and Visa – and will be spent via Facebook's stable of apps that include Messenger and WhatsApp.

This means there will be more scrutiny and transparency than traditional cryptocurrencies, though it remains to be seen how Libra will be regulated.

A Facebook spokesperson told The Independent: "We look forward to responding to policy makers' questions as this process moves forward."

Libra is set to launch at some stage in 2020.

French Economy and Finance Minister Bruno Le Maire said it was 'out of the question' that Libra becomes a sovereign currency (AFP/Getty Images)

Other criticism levelled at the Libra cryptocurrency is that it could be used as an "invasive and dangerous" form of surveillance.

Cryptocurrency expert Phil Chen, who pioneered HTC's first blockchain smartphone, said it could give the technology giant unprecedented access to its users' data.

"If you're concerned with Facebook knowing too much or having too much access to your private data, Libra will give Facebook even more direct access to your financial information," Mr Chen said.