Russia’s foreign minister has said leading British politicians are open to charges of slander over accusations that the Kremlin was involved in the 2006 murder of the former spy Alexander Litvinenko.

Litvinenko 'probably murdered on personal orders of Putin' Read more

Litvinenko, who had become a British citizen and critic of president Vladimir Putin, was poisoned with radioactive polonium by Russian agents Andrei Lugovoi and Dmitry Kovtun in London in an operation that was “probably approved” by Putin, a UK public inquiry found last week.

“Serious accusations have been made towards the Russian leadership yet exactly zero evidence has been presented,” Sergei Lavrov said on Tuesday. “All the conclusions were based on some sort of testimony by specially chosen witnesses, people who weren’t objective, or else on secret testimony.”

Lavrov complained that “we will probably never find out” how exiled oligarch Boris Berezovsky or celebrity nightclub owner David West, whose club was contaminated by polonium when Lugovoi and Kovtun visited it before Litvinenko’s murder, had died. West’s son admitted to stabbing his father to death in 2014, while Berezovsky was found hanged in 2013.

Alexander Litvinenko. Photograph: Reuters

“Given all this, it seems to me that if a well-versed lawyer took this up and analysed the facts and statements made by the leaders of the British government, they could be held accountable for slander,” Lavrov said.

The Litvinenko inquiry’s conclusions have been vigorously rejected by Russian officials including Lugovoi, who became an MP in 2007. Putin’s spokesman, Dmitry Peskov, called the findings an example of “subtle British humour”.

Lavrov said he agreed with the UK’s Foreign Office that the Litvinenko case would strain ties between the UK and Russia. “I fully agree with that. Except it’s not the Litvinenko case, but the drama around the Litvinenko case that will very seriously complicate our relations,” he said.

He accused the west of trying to “punish [Russia] for an independent foreign policy” and called for a “reset” in relations. But he also said “business as usual” with Europe and the US was impossible until Russia’s interests were taken into account.

Lavrov also denied reports that Igor Sergun, the recently deceased head of military intelligence, had travelled to Syria to ask president Bashar al-Assad to step down. Russia has neither offered Assad asylum nor received such a request, he said.