Prime Minister Andy Burnham has said it is “inconceivable” that Russia did not attempt to interfere in the 2016 EU referendum, but insisted he was not questioning the legitimacy of the result.

The comments have sparked a political row after Mr Burnham said during a podcast interview that he had received confirmation there had been Russian interference in the referendum campaign.

However, speaking in the Commons, the Prime Minister said he was referring to attempts to influence the democratic process rather than suggesting Russia had changed the outcome of the vote.

The 2016 referendum saw the UK vote to leave the European Union, with Leave winning by 51.9% to 48.1%.

Burnham’s comments

Speaking on The Rest is Politics podcast, Mr Burnham said he had asked officials after entering Downing Street whether Russia had interfered in the referendum.

“I’ve had the clear answer that, yes, there was,” he said.

He added that the UK had been “too much on the back foot” in explaining the extent to which foreign actors sought to disrupt political processes.

Mr Burnham did not provide details of the alleged activity or identify which intelligence agency had provided the information.

A No 10 spokesperson later said the Prime Minister believed it was highly likely Russia had attempted to influence the referendum, but did not believe those efforts had been successful.

Commons clash

The comments prompted a challenge from Conservative leader Kemi Badenoch, who accused Mr Burnham of implying the referendum result was illegitimate.

She asked him to confirm whether he accepted the result and whether he would publish evidence that Russian interference had affected the vote.

Mr Burnham replied that he had “implied no such thing”.

He said it was already established that Russia had sought to interfere in UK elections, adding: “We think it is inconceivable that this was the first time.”

He said the focus should be on protecting democracy from future interference.

Farage and Johnson reject claims

Reform UK leader Nigel Farage criticised the Prime Minister’s comments, saying: “The prime minister is a liar.”

He added: “There was no Russian interference – the Russian hoax has run all the way through this.”

Former prime minister Boris Johnson also challenged the claim, writing on social media that security services had told him in 2016 there was “no evidence of any successful interference” in the referendum.

Mr Johnson said: “Either the security services have changed their view – which would be very odd – or Burnham is lying about what he has been told.”

Previous investigations

Previous reviews have examined concerns about foreign interference in UK politics but have not established that Russia changed the result of the Brexit referendum.

A 2020 parliamentary Intelligence and Security Committee report criticised the government for failing to properly assess Russian activity and warned about the use of online influence campaigns.

Investigations into claims surrounding Leave.EU and businessman Arron Banks found no evidence of criminal offences under electoral law.

A more recent independent review of foreign influence in UK politics warned of attempts to undermine confidence in democratic institutions, but said the impact of such activity was difficult to measure.

The Brexit referendum result was decided by 17,410,742 votes to leave and 16,141,241 votes to remain — a margin of 1,269,501 votes.

Questions remain over intelligence briefing

It remains unclear whether Mr Burnham was referring to a new intelligence assessment or information provided during a private briefing by officials.

No newly declassified intelligence report has been published to support the claim, and the Prime Minister has not said which agency provided the information.

The Government has said protecting democratic institutions from foreign interference remains a priority.