The chairman of Hillary Clinton's presidential campaign has suggested that Russia hacked his emails to help Donald Trump, and implied that the Trump campaign may have colluded with Russian intelligence over the “criminal hack”.

Thousands of emails sent and received by John Podesta, one of Mrs Clinton’s most senior advisers, have been published by Wikileaks, causing serious headaches for the campaign less than one month from election day.

Mr Podesta has now said the FBI is investigating Russia’s apparent role in the “criminal hack”, and hinted at possible coordination between the Trump campaign and the Kremlin.

He said it was a “reasonable conclusion” that the campaign and Roger Stone, a Trump confidante, had received “advanced warning” about the hack.