LONDON — Fears of Russian interference reared their head in the U.K. election this weekend after social media platform Reddit said it believed confidential British government documents were posted to the site as “part of a campaign that has been reported as originating from Russia."

Reddit launched an investigation after opposition Labour Party leader Jeremy Corbyn brandished the leaked documents at a press conference last month.

The 451-page dossier appeared to reveal rounds of trade negotiations with the U.S. for a post-Brexit trade deal included mention of the country's beloved National Health Service. Labour claimed they proved Prime Minister Boris Johnson would put the NHS "up for sale" to secure a deal with President Donald Trump.

The British government has not denied the authenticity of the documents. NBC News has not verified their authenticity.

Johnson, whose ruling Conservative Party leads in the polls entering the final week, has denied Corbyn's claims about what they show.

A British government spokesperson told NBC News Sunday that “online platforms should take responsibility for content posted on them, and we welcome the action Reddit have taken."

“The U.K. government was already looking into the matter, with support from the National Cyber Security Centre," the spokesperson said.

“We do not comment on leaks, and it would be inappropriate to comment."

Reddit said late Friday that its investigation into the posts related to the leak revealed "a pattern of coordination" by suspect accounts that were similar to a Russian campaign called "Secondary Infektion" discovered on Facebook earlier this year.

The site also said it had banned 61 accounts suspected of violating policies against vote manipulation related to the original post, which was published in October.

Corbyn has not revealed how his party obtained the documents but defended the decision to use them.

Asked about Reddit's conclusions at a campaign stop Saturday, Corbyn said the news was an “advanced stage of rather belated conspiracy theories.''

"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. And if there has been no discussion with the USA about access to our health markets, if all that is wrong, how come after a week they still haven't said that?" he added.

He also criticized the government for failing to release a Parliamentary intelligence committee report on Russian interference in British politics before the election campaign began.

Thursday's vote was called in an effort to break the deadlock that has left the future of the country's relationship with the European Union uncertain.

But the future of Britain's health care has emerged as a powerful rejoinder to the notion of a purely 'Brexit election.'

Asked about the source of the leak this weekend, Johnson said: "I do think we need to get to the bottom of that."

Culture minister Nicky Morgan claimed the leak raises concerns of Russian influence on British democracy and said the government is taking steps and "watching for what might be going on."

"From what was being put on that (Reddit) website, those who seem to know about these things say that it seems to have all the hallmarks of some form of interference,'' Morgan told the BBC. "And if that is the case, that obviously is extremely serious.''

But if Russia was behind the leak, its aim may not have been to help any particular side in the election, Lisa-Maria Neudert, a researcher at Oxford University’s Project on Computational Propaganda, told Reuters.

"We know from the Russian playbook that often it is not for or against anything," she said.

"It’s about sowing confusion, and destroying the field of political trust."