Labour leader declines to reveal source of documents but says PM has questions to answer on Russian donations

Jeremy Corbyn declined to disclose the source of documents used as evidence that the NHS would be “on the table” in a post-Brexit UK-US trade deal, after Reddit told of a link to a Russian interference campaign.

The Labour leader brandished the unredacted documents at a press conference last week, saying they revealed the US was seeking “total market access” after the UK left the European Union and therefore undermined Boris Johnson’s claims that the NHS would not be part of any trade talks.

However, the Conservative party said the material had already been online for two months and was simply readouts from meetings of the UK-US trade and investment working group. The international trade secretary, Liz Truss, said the price that the NHS paid for drugs would not be “on the table”.

There is heightened scrutiny over the origin of the documents – the legitimacy of which has not been called into question – after Reddit said on Friday it believed they had been leaked and then posted by an account which was part of a dubious campaign reported to have originated in Russia.

But Corbyn refused to say how he obtained the documents and dismissed a suggestion that Labour had benefitted from a Russian trolling operation.

“This is such nonsense,” he said on Saturday at a zero-waste shop in Barry, Wales. “This is such an advanced state of rather belated conspiracy theories by the prime minister. When we released the documents, at no stage did the prime minister or anybody deny that those documents were real, deny the arguments that we put forward.

“We obtained those documents. We believed those documents to be correct and nobody until yesterday denied the correctness of those documents. The issue is there should be no interference in British politics by anybody else.

He added: “The prime minister has answers to give, which he refuses to do, about Russian donations to the Tory party or the report that he is sitting on about Russian interference in British politics. Of course there should be no interference in our British political system by Donald Trump or the Russians.”

Johnson said on Saturday that the source of the documents must be established. “Well I do think we need to get to the bottom of that,” he told Sky, from the side of a football pitch near Stockport.

“As far as I’m aware we haven’t yet established the truth about that. But what I certainly think is that document, whatever it was intended to prove, did not prove what Jeremy Corbyn and the Labour party hoped that it would prove. And I’m afraid it was just another distraction.”

Reddit said in a statement that it was recently made aware of a post made in October that included leaked documents from the UK, which was then reposted by a second account.

“We investigated this account and the accounts connected to it, and today we believe this was part of a campaign that has been reported as originating from Russia,” the company said in a statement.

It added that it had identified and suspended 61 accounts that attempted to further promote the leaked papers, including that of a user called Gregoriator. “All of these accounts have the same shared pattern as the original Secondary Infektion group detected, causing us to believe that this was indeed tied to the original group,” it said.

Pockets of accounts had worked together to “upvote” the posts using vote manipulation to make them more visible to users of the platform, Reddit said.

The news also highlighted how the UK’s democratic process was vulnerable to Moscow’s influence and placed Johnson under renewed pressure to release the parliamentary report into Russian meddling before the general election.