"That should be an absolute condition because there is no doubt, we have seen it in our country, we have seen it in Europe, we have seen it here that Russia in particular is determined to try to shape the politics of Western democracies, not to our benefit but to theirs.

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"There's no doubt of the role that Russia played in our 2016 election and is continuing to play. There's a lot of evidence that Russia played in the Brexit election ... The fact that the current government won't release this report by your own government should raise some questions."

Johnson refused to release the report, handed to him in October, from the Common's intelligence committee which examines Russian activities in the UK. The report can only be released while the parliament is constituted, meaning it cannot now be published until after the December 12 election, given parliament was dissolved last week.

A whistleblower has raised concerns with Labour MPs about Johnson's chief aide Dominic Cummings, the strategist behind the Vote Leave campaign which Boris Johnson publicly headed in 2016.

Cummings spent three years in Russia in his 20s and is claimed to have developed relationships with key backers of President Vladimir Putin.

That prompted warnings that the sanctity of the Five Eyes intelligence-sharing network could be at risk, amid reports in The Sunday Times that spooks are withholding top-secret information from Cummings.

Clinton said the world was in "the midst of a real struggle about the future of democracy" and urged the UK to resolve Brexit.

"Authoritarians are on the rise, they seem to have an attraction to even the current incumbent in the White House and others, so our real hope is that the UK sorts itself out.

"We need a strong UK, we need a UK with smart, sensible, forward-looking leadership."

Clinton's comments were backed by numerous MPs including the Australian-born Labour Member for Hornsey Catherine West, who told The Sydney Morning Herald and The Age said her constituents had a right to know what the report said.

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"MPs don’t know what the Johnson government is hiding and why the report into Russian interference in elections cannot be released immediately," she said.

"Whether it’s the PM’s links to wealthy Russian oligarchs or questions over the PM’s adviser and the company he kept during his four years in Russia, our constituents have a right to read this parliamentary report. I say to Mr Johnson: have the report released immediately."

Labour frontbencher David Lammy said on Twitter:"We can't let Boris off the hook."

Yvette Cooper, the Labour chair of the Home Affairs Select Committee, said: "I agree with Hillary. What does Boris Johnson have to hide?"