The long-awaited Russia report from the UK parliament’s intelligence and security committee is due to be released on Tuesday morning, nine months after its publication was blocked by Boris Johnson before the general election. An examination of the reach of the Kremlin into UK politics and public life, the document is the product of 18 months’ work by a cross-party committee taking evidence in secret from British intelligence and independent experts. Downing Street has repeatedly sought to downplay the significance of its contents, even though the prime minister refused to clear it as required by law last October, preventing its publication for months on end. Evidence was submitted by the former spy Christopher Steele, accusing senior UK government ministers, including Johnson and the former prime minister Theresa May, of ignoring claims the Kremlin had a “likely hold” over Donald Trump. The MI6 veteran also told the committee there was evidence the Kremlin tried to covertly fund Brexit and influence the result of the 2016 referendum, although it is unclear how far he influenced the final document. Publication of the document comes days after the nine-strong committee rejected Johnson’s choice of chairman, the former minister Chris Grayling. Members voted by five to four to support the veteran Conservative Julian Lewis instead. An enraged Downing Street stripped the party whip from Lewis, who had been a Conservative MP since 1997, but has since backed away from trying to remove him from the committee’s membership. A day later the reconstituted committee agreed to release the Russia report, which has to be published when parliament is sitting – and coincides with the visit to the Uk of the US secretary of state, Mike Pompeo. Trump has been dogged by allegations that his election victory over Hillary Clinton in 2016 was aided by Russia, mainly by the hacking of Democratic party emails in the run-up to the vote.