LONDON -- Britain will expel 23 Russian diplomats accused of engaging in intelligence activities and cancel an invitation for a visit by Russian Foreign Minister Sergei Lavrov, Prime Minister Theresa May said on Wednesday.
The measures are part of a "full and robust" response to the use of a Russia-developed nerve agent to poison a former double agent and his daughter in Britain, and Moscow's refusal to account for the presence of the toxin, May told Parliament.
Britain will also send no senior officials or members of the royal family to this year's football World Cup in Russia, suspending "all planned high-level contacts" between London and Moscow, she said.
The Russian embassy in London condemned the expulsion of the diplomats as a "hostile action" that is "totally unacceptable, unjustified and short-sighted."
"All the responsibility for the deterioration of the Russia-UK relationship lies with the current political leadership of Britain," the embassy said in a statement on its website.
Britain has summoned Russian Ambassador Alexander Yakovenko to inform him that the 23 Russian diplomats were being declared personae non gratae, the statement said.
Ahead of May's statement, the Foreign Office said on Twitter that Britain had called for an urgent meeting of the UN Security Council to "update council members on the investigation into the nerve agent attack in Salisbury."
"The use of a nerve agent in Salisbury follows a well-established pattern of Russian state aggression," it said in a second tweet linked to a slideshow listing alleged Russian contraventions of international rules.
May said the 23 diplomats had been given one week to leave Britain after they were "identified as undeclared intelligence officers."
"This will be the single biggest expulsion for over 30 years and it reflects the fact that this is not the first time that the Russian state has acted against our country," she said, citing the poisoning of former Russian spy Alexander Litvinenko in 2006.