France has said it will block the development of Facebook's Libra cryptocurrency as it poses a threat to "monetary sovereignty".

At the opening of an OECD conference on cryptocurrencies, French economy and finance minister Bruno Le Maire said: "I want to be absolutely clear: In these conditions, we cannot authorise the development of Libra on European soil."

Facebook's Libra cryptocurrency was announced earlier this year and is set to launch at some point in 2020. Despite Libra having certain technological similarities with bitcoin, its creators hope that its more centralised infrastructure will allow it to become a global currency that could rival the US dollar.