It is "inexplicable and shameful" that the UK government has not yet published a report on alleged Russian interference in British politics, Hillary Clinton has told the BBC.
The report has formal security clearance, but it will not be released until after the 12 December election.
"Every person who votes in this country deserves to see that report before your election happens," the former US presidential candidate said.
No 10 denies it is suppressing it.
The report by Parliament's Intelligence and Security Committee examines Russian activity in UK democracy.
It includes allegations of espionage, subversion and interference in elections.
It contains evidence from UK intelligence services such as GCHQ, MI5 and MI6 concerning covert Russian attempts to influence the outcome of the 2016 EU referendum and 2017 general election.
The report was finalised in March and referred to No 10 on 17 October.
But approval for its publication has yet to be given - and is not due to happen until after polling day.
MPs on the intelligence committee have been highly critical of that outcome, but the government has said the timing is not unusual.
Speaking to BBC Radio 4's Today programme while in the UK on a book tour, Mrs Clinton said she was "dumbfounded" that the government would not release the report.
"That should be an absolute condition," she said.
"Because there is no doubt - we know 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."
She also told BBC Radio 5 Live's Emma Barnett: "I find it inexplicable that your government will not release a government report about Russian influence. Inexplicable and shameful."