British Prime Minister Andy Burnham said Russia interfered in the 2016 Brexit vote, although his office later stated that Moscow failed to influence the result and the decision to leave the European Union was legitimate.
Burnham, who took over as Britain's leader in July and said last month that Britain could consider rejoining the European Union in the future, is the first British prime minister to say openly there was evidence of Russian interference in the vote.
He made the comment as he warned voters in France and Germany about Moscow-backed efforts to influence their politics.
"I asked the question coming to Downing Street, was there interference in the 2016 referendum from Russia? And I've had the clear answer that yes, there was," Burnham said in an interview with The Rest Is Politics podcast.
Burnham did not spell out how he believed that Russia interfered in the referendum and gave no details on what evidence this statement was based.
The Russian embassy in London did not respond to a request for comment.
Russia has previously denied meddling in the Brexit vote, casting Britain as gripped by anti-Russian hysteria.
Burnham's Russian interference claims contrast with Boris Johnson's position
Burnham's comments mark a departure from those of former Prime Minister Boris Johnson, who campaigned to leave the EU, and said in 2020 there was no evidence of Russian interference in the referendum.
Britons voted 52%-48% to leave the EU in 2016, plunging the country into its biggest political crisis since World War Two.
Junior foreign office minister Stephen Doughty clarified Burnham's remarks on Monday, saying there was no evidence that Russia successfully interfered in the referendum.
Asked whether interference could have changed the result, he told Sky News: "They haven't succeeded."
A spokesman for Burnham also said the government believed the referendum result was legitimate.
Nigel Farage, a leading campaigner for Brexit, called Burnham a "liar" and said he had "all sorts of bizarre ideas."
Burnham said in the podcast voters in European democracies needed to be better informed about efforts to disrupt their politics.
"I mean, these things are important now to put clearly on the record, and I believe, help voters in Germany and France understand that some of this politics is instigated via our enemies, namely Russia," he said.
2020 UK intelligence report failed to establish Russian interference in Brexit vote
A 2020 report by parliament's Intelligence and Security Committee found Britain's government had failed to establish whether Russia meddled in the 2016 referendum.
The report also found that Russia had sought to influence Scotland's 2014 independence referendum, in which voters rejected independence.