Facebook has been accused of “threatening the very values underpinning our democracy” by allowing anti-Semitic conspiracies to spread on its social network and commissioning “vile propaganda” about billionaire financier George Soros.

The accusations were made by Open Society Foundations, a non-profit group founded by Mr Soros, following an investigation into Facebook's alleged use of underhand and aggressive tactics designed to divert attention away from its own scandals.

The tech giant hired Definers Public Affairs, a Washington DC based political consultancy specialising in opposition research, to attack critics of the firm, according to the New York Times.

Definers Public Affairs sent journalists a research document connecting Mr Soros to “a broad anti-Facebook movement”, according to the New York Times. It encouraged journalists to look into links between Mr Soros and groups such as "Freedom from Facebook", a lobby firm that campaigns against Facebook.

Patrick Gaspard, president of Open Society Foundations, said the strategy was “dangerous."