- Additional reporting by Press Association
UK Labour and the Lib Dems are accusing Boris Johnson of hiding a report, which exposes the scale of the threat from Russia to Britain's democracy.
The British Prime Minister received the findings a fortnight ago, but hasn't allowed it to be published.
Russia's previously been accused of attempting to disrupt foreign elections.
Former attorney general Dominic Grieve, who has seen the document, stressed its publication is essential ahead of the General Election, with it containing information “germane” to voters.
UK Labour leader Jeremy Corbyn suggested, however, that the report hasn't been published as the government want to delay it until after parliaments dissolution.
"If the report has been called for and written and should be in public domain what have they got to hide?"
Liberal Democrat leader Jo Swinson also called on the Government to stop “keeping it a secret”.
Mr Grieve, chairman of the Intelligence and Security Committee at Parliament, has accused the Prime Minister of sitting on the report ahead of the December 12 vote.
The independent MP, who was exiled from the Tories by the PM over his no-deal Brexit opposition, is calling on the Conservative leader to publish the committee’s report before Parliament is dissolved on Tuesday.
“I cannot think of a reason why he should wish to prevent this report being published,” Mr Grieve told BBC Radio 4’s Today programme.
Asked if there is useful information in the report for voters, he said: “Yes I think there is. It’s about information. I want to emphasise I’m not about to explain what’s in the report, I’m not allowed to and I wouldn’t dream of doing so.
“But the report is informative and people are entitled to information and it seems to us that this report is germane because we do know and I think it is widely accepted that the Russians have sought to interfere in other countries’ democratic processes in the past.”
The House of Commons was previously told the report was sent to the PM on October 17.
A Downing Street spokeswoman said: “There are a number of administrative stages/processes which reports such as this – which often contain sensitive information – have to go through before they are published.
“This usually takes several weeks to complete. The committee is well informed of this process.”
But Ms Swinson called for urgency in the report’s publication.
“I think this is a very serious issue. The idea that other countries meddle in our democratic processes is deeply worrying,” she told the PA news agency.
“He (Mr Grieve) has seen it and he says this is something that should be published before we embark on an election and that makes perfect sense to me.
“Because, if there is information that we should know about what has happened in previous democratic events and who has tried to interfere, the public has a right to know and the Government shouldn’t be keeping it a secret.”
Parliament is expected to sit on Monday and Tuesday ahead of dissolution although proceedings could be brought to an end sooner, which may prevent publication.
Commons Speaker John Bercow called on Leader of the House Jacob Rees-Mogg to expedite the publication.