The UK government's Intelligence and Security Committee (ISC) revealed in a report yesterday that Russia sees the country as one of its "top targets" in the West.
The London-based ISC's inquiry covers a number of topics, including disinformation campaigns, cyber tactics and Russian expatriates in the UK, the BBC reported.
But much of the "highly sensitive" detail will not be published due to fears Russia could use the evidence to threaten the UK.
The long-awaited report said Russian influence in the UK was "the new normal", and accused successive governments of welcoming the country's oligarchs "with open arms".
It said the UK was "clearly a target" for disinformation campaigns around its elections and called for an "immediate action" to help intelligence services tackle "this very capable adversary".
The committee also criticized No 10 for delaying the report's publication.
The Downing Street was accused of holding back its release ahead of December's UK election – which it has denied.
But speaking at a press conference to launch the report, one of the ISC's committee members, Kevan Jones, criticized Prime Minister Boris Johnson for not signing it off sooner, saying there was "no reason for delay".
Another ISC committee member, Stewart Hosie said no one in government wanted to touch the issue of Russian interference with a "10-foot pole" and no one knew if Moscow had tried to interfere with the 2016 referendum "because they did not want to know"..