MOSCOW — The war of words between Russia and Britain over a former spy’s poisoning got uglier Wednesday when UK foreign secretary Boris Johnson called it vomit-inducing that Russian President Vladimir Putin is rejoicing over hosting the World Cup. Russia shot back that Johnson is ‘‘poisoned with venom of malice and hate.’’

The heated exchange came in the deepening diplomatic crisis over the March 4 poisoning of Sergei Skripal and his daughter in the English city of Salisbury. Britain asserts that Russia used a military-grade nerve agent known as Novichok in the attack, which left Skripal and his daughter in critical condition. Moscow has denied any involvement in the poisoning.

Johnson on Wednesday repeated Britain’s position that responsibility for the poisoning leads ‘‘back to the Russian state and those at the top.’’

Johnson agreed with a ­Labour lawmaker who likened the World Cup hosted by Russia this summer to Adolf Hitler’s use of the 1936 Olympics for political purposes.

‘‘I think the comparison with 1936 is certainly right,’’ he said. ‘‘I think it’s an emetic prospect, frankly, to think of Putin glorying in this sporting event.’’

The Russian Foreign Ministry’s spokeswoman, Maria Zakharova, said Johnson is ‘‘poisoned with venom of malice and hate, unprofessionalism, and boorishness.’’

‘‘It’s scary to remember that this person represents the political leadership of a nuclear power,’’ she said.

Johnson’s comments, Zakharova, added, reflected London’s efforts to cast Russia as an enemy using the most absurd reasons in order to boycott the World Cup.

‘‘But at what price?’’ she said. ‘‘At the price of provocations, setting nations and people against one another, and undermining international peace and stability. Isn’t the price too high?’’

Zakharova noted that Johnson’s comments about the 1936 Olympics and the World Cup were an ‘‘unacceptable and unworthy’’ parallel toward Russia, a ‘‘nation that lost millions of lives in fighting Nazism.’’