Nigel Farage is demanding an apology after the long-awaited report into Russian interference in British democracy concluded no evidence could be found of meddling in the Brexit referendum of 2016.
But the Intelligence and Security Committee said it could not rule out any attempted interference in that poll because the government "actively avoided" investigating it.
The ambiguity has resulted in Remainers claiming the UK's democratic processes were not protected, potentially cheating them out of a fair contest, but Brexiters claim the report vindicates the result.
Since the UK voted to leave the EU, many Brexit opponents have claimed the result was swayed by Russian actors influencing people online.
Following the report's release, many Brexit supporters, including figurehead Mr Farage and billionaire backer Arron Banks, took to Twitter to call for apologies.
Former Ukip leader Nigel Farage tweeted: “Years of lies and smears from Remain politicians and much of our media. There is no evidence of Russian involvement with Leave.EU or me in the referendum.
“It was all a hoax — apologies are now required.”
Mr Banks retweeted a comment by his friend and fellow Brexit supporter Andy Wigmore, who also asked for an apology.
There were hundreds of responses to Mr Farage's tweet, with many questioning whether he had read the report and pointing to lines in it which say the threat was not investigated.
But the Brexit supporting government, with a Cabinet made up of Eurosceptics, has also taken the report as proof the referendum was won legitimately.
Did the UK fail to take the threat from Russia seriously enough?
In a response issued immediately after the report was released, the government said: “We have seen no evidence of successful interference in the EU Referendum."
And Boris Johnson is “absolutely” confident the 2016 European Union referendum result was fair, the his official spokesman said.
“We have seen no evidence of successful interference in the EU referendum,” the spokesman said, as he confirmed the Government would not order an investigation of Russian activities around the vote.
“Our intelligence and security agencies produce regular assessments of the threat posed by hostile state activities, including any potential interference in past or current UK democratic processes.”
In a 20-page response to the report, the government said there was no need to investigate alleged Russian activity during the Brexit referendum because regular assessments are made by Intelligence and Security Agencies.
An investigation by the Intelligence and Security Committee found Russia did attempt to influence the Scottish independence referendum in 2014 but it said it the government "did not take action to protect the UK’s process in 2016".
Several social media users who previously supported Britain remaining in the UK, such as former Labour spin doctor Alastair Campbell, said the report showed "Brexit is a fraud".
He told ITV News he'd "always thought that the referendum was a fraud and always felt that it was won on one set of lies and lots of other sets of lies have been practiced since".
He added: "They lied systematically and I fear that these three things together; Brexit, Johnson - a proven liar as prime minister with no real commitment to standards in public life - and now this report.
"They are all symbols of a country, I'm afraid, that's chosen its own decline."
Liberal Democrat acting leader Sir Ed Davey said the government had been "wilfully negligent" by not investigating the part Russia played in the Brexit referendum.
"We need a proper investigation into the full role that Russian interference has played in our democracy," he said.
He accused Boris Johnson of refusing “a cross-party call to launch an inquiry because he is worried about what it might find”.
“This is a green light for Russia to interfere with our democracy in future, knowing there will be no consequences,” he tweeted.
Guy Verhofstadt, chief Brexit negotiator for the European Parliament, tweeted: “Brexit was always a gift to Putin because it weakened the European Union & left Britain divided, isolated. The #RussiaReport shows just how many questions remain unanswered.”
Meanwhile, Scotland’s First Minister said she has “no objection” to an inquiry being launched into Russian interference in the Scottish independence referendum.
Speaking at the Scottish Government’s coronavirus briefing on Tuesday, hours after the report was published, Nicola Sturgeon said governments should not be “complacent” about the possibility of interference in democratic processes.
The report, which was due to be published before the 2019 general election but faced months of delays, said there is “credible open source commentary” suggesting Russia used influence campaigns during the independence referendum campaign in 2014.
Ms Sturgeon said: “If there’s to be an inquiry into that – and I would have no objections, to the contrary – it is for the UK Government to do.”
The First Minister said she hopes the report will lead to a “much more rigorous approach” by the UK Government in dealing with interference.
She said: “I don’t think you can draw any conclusions from the three lines or thereabouts that the report has on the Scottish independence referendum.”
The First Minister added she did not think her values, along with those of the SNP and the wider independence movement “could be further removed from the values that Vladimir Putin and the Russian regime stand for”.