Russia's ambassador to the United Kingdom warned Wednesday that British Prime Minister Theresa May’s expulsion of Russian diplomats over an alleged assassination attempt is a "provocation."

“I've just had a meeting at the Foreign Office and I told them that everything the British government is doing at the moment is absolutely inadmissible and we're considering their steps as a provocation,” Alexander Yakovenko, Russia’s top diplomat in the U.K., said according to Russia's state-run media.

May expelled 23 diplomats and canceled a visit from Russian Foreign Minister Sergey Lavrov as part of suspension of high-level contacts between the two nations. The flurry of punitive measures is a response to the poisoning of a former Russian military intelligence officer who worked as a double agent on behalf of the U.K. Lavrov, denying involvement, argued that Russia had no “motive” for the incident.

"Such motives might certainly exist in the minds of those who would like to push ahead with the Russophobic campaign in all spheres of human activity without an exception,” Lavrov said, according to TASS.

The former spy, who was released to British territory as part of a spy exchange in 2010, was attacked by “a military-grade nerve agent,” May said. On Monday, she called for an explanation from Russia by Wednesday.

“Should there be no credible response, we will conclude that this action amounts to an unlawful use of force by the Russian state against the United Kingdom,” she told the House of Commons.

Russian officials dismissed her deadline as disrespectful, and said such issues should be investigated under processes set by the Chemical Weapons Convention and the Organization for the Prohibition of Chemical Weapons. "But no such request was sent," Lavrov said. "You know, this kind of conceit shows in almost all the steps London has been taking — not only in this particular case.”

Instead, the British have called for an emergency session of the United Nations Security Council, scheduled for Wednesday afternoon.