A parliamentary report into Russia's covert action in Britain will not be published until after the election – even as a peer called the delay by the government "an irregular state of affairs".
Prime Minister Boris Johnson must give the green light for the findings of the special inquiry into Russia by the Intelligence and Security Committee to be released.
The file was submitted to Downing Street on 17 October.
Senior politicians and peers have said the government typically provides confirmation within 10 days. However, this has not yet happened.
Russia is accused of using unconventional forms of warfare to attack Western democracies, including in the UK.
This includes allegations of spreading fake news and disinformation to exploit divisions during the Brexit referendum.
Security agencies in the US believe the Kremlin launched an influence operation against then Democratic candidate Hillary Clinton in the US presidential election.
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The disinformation attack also worked to promote then candidate Donald Trump.
President Vladimir Putin is also accused of assassinating opponents.
Britain blames Russia's GRU military intelligence agency for the attempted poisoning of former Russian spy Sergei Skripal and his daughter Yulia in Salisbury using a novichok nerve agent.
Whitehall sources said on Monday afternoon the report would not be published by the time parliament rises for the election at 12.01am on Wednesday.
The development came as Lord Anderson, the UK's former independent reviewer of terrorism legislation, used an urgent question in the House of Lords to ask the government why the report has not yet been released and to call for its publication.
Lord Howe, responding for the government, said this would happen "in due course once the usual processes have been completed".
Lord Anderson said he rejected reasons given by the government for what he described as a hold-up.
He said an excuse about the need for time to ensure redactions are made was unnecessary as the document has already been seen by the security and intelligence agencies, with overly sensitive material already concealed.
Lord Anderson also dismissed an argument that time was required to devise a response, noting that typically a report is published and the government response follows within 60 days.
He said the situation was an "irregular state of affairs", before adding: "This unjust delay undermines the Intelligence and Security Committee. It invites suspicion, I'm afraid, of the government and its motives. Will the minister advise Number 10 to think again?"