MOSCOW - Russian Foreign Minister Sergei Lavrov and British Foreign Secretary Boris Johnson clashed Friday over Russia's alleged interference in the Brexit vote even as they sought to thaw ties after years of antagonism.

During the first official visit by a foreign minister from London in five years, the outspoken Johnson tried to open lines of communication and the two diplomats made attempts to show their two countries were willing to overcome years of differences.

But the two appeared to clash over allegations that Russia had sought to influence the Brexit vote last year, with Lavrov urging Johnson to come up with hard evidence proving Russia's alleged interference.

Lavrov said he welcomed Johnson's November comment in which the British minister said he saw no evidence, "not a sausage", that Russia had interfered in British elections.

"Not successfully," Johnson interrupted. Lavrov then accused his British counterpart of contradicting him to avoid "criticism back home" and to safeguard "his reputation."

"It's your reputation I'm worried about, Sergei," Johnson hit back jokingly in a tense exchange through interpreters.

Lavrov said recent accusations of Moscow's meddling in Western political systems have been invented by the West and that Moscow had yet to see any "concrete evidence" to back them up.

"I think you've made it all up in your Western company and unfortunately you are hostages to this subject."

"It's very difficult to climb down from the fence." Following the 2016 referendum on Brexit, in which Johnson campaigned to leave the EU, Britain has joined the growing number of Western countries accusing Russia of interfering in their political systems.

Accusations that the Kremlin is meddling in Western domestic affairs have heightened fears over the influence of Russian hackers, trolls and state-controlled media.

While the first accusations against Moscow came following a 2016 hack attack on the US Democratic Party's servers, they rapidly multiplied after Trump's election.

In a major foreign policy speech last month, British Prime Minister Theresa May accused Russia of "weaponising information" and "threatening the international world order on which we all depend."

A new report published by researchers from Oxford University this month found that Russian "trolls and bots" active ahead of the Brexit vote "contributed relatively little to the overall Brexit conversation."