Five calling cards indicate 'Secondary Infektion' method that was used to spread disinformation in the US

The Kremlin has fuelled the growing row around leaked government documents published by Labour as it failed to deny the involvement of Russian hackers.

Senior MPs have called for an urgent investigation into how Labour obtained the classified information amid growing evidence linking the leak to Moscow.

Jeremy Corbyn hinted yesterday that he had downloaded minutes of US-UK trade talks from a website where investigators increasingly believe it had been placed by Russia.

The Kremlin failed to deny being behind the leak yesterday as it used the row to mock Boris Johnson by suggesting it was being used to distract attention from his “own problems”.

Iain Duncan Smith, the former Conservative Party leader, said it was now imperative that the Cabinet Office should launch an investigation to find out how the documents found their way online and into Mr Corbyn’s hands.