The Government was slow to recognise the potential threat posed by Russia to British democratic processes and did not properly consider whether Moscow could interfere in the Brexit referendum until after the event, the Intelligence and Security Committee found.

A long-delayed report on Russia’s activities concluded that the UK only belatedly realised the threat to political processes despite alarm bells ringing over the 2014 Scottish referendum.

The intelligence agencies and Government departments treated the issue as a “hot potato” with no-one getting a grip on the problem, the committee said.

The Government said there was “no evidence” of successful Russian interference in the Brexit vote but the committee – which oversees the work of Britain’s spies – suggested that there was no proper investigation.

MI5 provided just “six lines of text” when asked whether there was secret intelligence on the issue of potential Russian meddling in the referendum.

But the Government – led by prominent Brexiteer Boris Johnson – has rejected the committee’s call for a full analysis of whether Vladimir Putin’s government did attempt to influence the result of the 2016 vote.

The report was drawn up by the ISC’s members in the last parliament and its publication was delayed by Mr Johnson’s decision to call a general election and the slow process of appointing a successor committee.

The committee said there was “credible open source commentary” indicating Russian influence campaigns in relation to the Scottish independence referendum in 2014, but it was only after the “hack and leak” operation in the Democratic National Committee in the US – with the emails made public a month after the 2016 EU referendum – that the Government “belatedly realised the level of threat which Russia could pose in this area”.

Other key findings include:

– Russian influence in the UK is the “new normal” after successive governments welcomed the oligarchs with open arms, giving some of Mr Putin’s allies connections “at the highest levels” to UK companies and political figures.

– The rise of the Russian elite in “Londongrad” has fuelled an industry, with British security companies seeking compromising material – kompromat – on rival oligarchs and dirty money being recycled through a “London laundromat”.

– Social media companies are failing to play their part to remove covert “hostile state material” and the Government should name and shame firms that fail to act.

– A number of Members of the House of Lords have business interests linked to Russia, or work directly for major firms linked to the Kremlin – these relationships should be carefully scrutinised, given the potential for the Russian state to exploit them.

– Blunders by Russian agents in the poisoning of Sergei and Yulia Skripal in Salisbury in March 2018 and the attempted infiltration of the Organisation for the Prohibition of Chemical Weapons (OPCW) demonstrate that Moscow’s spies are not infallible but “it would be foolhardy to think that they are any less dangerous because of these mistakes”.

The committee said: “It has been clear for some time that Russia under Putin has moved from potential partner to established threat, fundamentally unwilling to adhere to international law – the murder of Alexander Litvinenko in 2006 and the annexation of Crimea in 2014 were stark indicators of this.

“We therefore question whether the Government took its eye off the ball because of its focus on counter-terrorism: it was the opinion of the Committee that until recently the Government had badly under-estimated the response required to the Russian threat – and is still playing catch-up.”

The heavily redacted report, drawn up under the chairmanship of Remain-supporting Dominic Grieve, noted “widespread public allegations that Russia sought to influence the 2016 referendum”.

“Open source studies have pointed to the preponderance of pro-Brexit or anti-EU stories on RT and Sputnik, and the use of ‘bots’ and ‘trolls’ as evidence of Russian attempts to influence the process,” the report said.

“We have sought to establish whether there is secret intelligence which supported or built on these studies.

“In response to our request for written evidence at the outset of the inquiry, MI5 initially provided just six lines of text.”

The committee said the Government “had not seen or sought evidence of successful interference in UK democratic processes” and called for the intelligence community to carry out a full assessment of potential Russian meddling in the 2016 referendum.

But the Government rejected the call, saying “we have seen no evidence of successful interference in the EU referendum”.

The Government also denied the suggestion it had “badly underestimated” the Russian threat.

Foreign Secretary Dominic Raab said: “We’ve been clear that Russia must desist from its attacks on the UK and our allies.

“We will be resolute in defending our country, our democracy and our values from such hostile state activity.”

ISC member and SNP MP Stewart Hosie said: “There has been no assessment of Russian interference in the EU referendum and this goes back to nobody wanting to touch the issue with a 10ft pole.”

Labour ISC member Kevan Jones said the Government has to “take responsibility” for failing to look into possible Russian interference.

Asked if security services were partly responsible for not investigating the matter, Mr Jones said to “sidestep” and blame the intelligence agencies was “not fair”.

Shadow foreign secretary Lisa Nandy said: “It is extraordinary that the Prime Minister took the political decision last October ahead of the general election to block the publication of this important report that systematically goes through the threat Russia poses to the UK’s national security.”