MOSCOW — Russia on Saturday ordered 23 British diplomats to leave the country within a week, escalating a diplomatic crisis after a former Russian spy and his daughter were poisoned with a military grade nerve agent on British soil.
The order came days after Prime Minister Theresa May of Britain expelled the same number of Russian diplomats and called off high-level contacts between the two governments.
The Russians also ordered the closing of the British Council, a cultural and educational organization, in Russia, and revoked permission for the British consulate general in St. Petersburg.
May said Saturday that the UK may take further actions against Russia but did not elaborate.
The Russian announcement came after the British ambassador, Laurie Bristow, was summoned to the Foreign Ministry in Moscow on Saturday morning.
In a statement, the Foreign Ministry cast Russia as the aggrieved party, asserting that Russia was acting “in response to the unfounded accusation against the Russian Federation for what happened in Salisbury.” It added, “The British side is warned that, in the case of further actions of an unfriendly character toward Russia, the Russian side reserves the right to take other answering measures.”
The Kremlin delayed its response for three days until a day before national elections on Sunday, for which President Vladimir Putin has campaigned while casting himself as a defender of Russia against Western aggression.
The spy, Sergei V. Skripal, and his daughter, Yulia Skripal, were found unresponsive on a park bench in the cathedral city of Salisbury, England, after being attacked on March 4. British officials said the lethal nerve agent, Novichok, had been created in the Soviet Union in the 1970s and ’80s.
The Kremlin has flatly denied any involvement in the attack, even as state television announcers have pointedly referred to the poisoning as a warning to traitors.
The case has roiled relations between the two countries, with Britain announcing that in addition to other measures, no ministers or members of the royal family would attend the World Cup hosted by Russia this summer.
Bristow, the British ambassador, told journalists in Moscow on Saturday, “We will always do what is necessary to defend ourselves, our allies, and our values against an attack of this sort.”
The crisis, he added, “has arisen as a result of an appalling attack in the United Kingdom, the attempted murder of two people using a chemical weapon developed in Russia and not declared by Russia” with the Organization for the Prohibition of Chemical Weapons, as is required by treaty.
The tit-for-tat expulsions were the second such episode after geopolitically-related poisonings in Britain.
After the British government blamed a Russian agent for adding a lethal dose of the radioactive element polonium-210 to tea sipped by Alexander V. Litvinenko, a former Russian Security Service officer, Britain expelled four Russian diplomats in 2007, and Russia responded in kind.
In December 2016, the Obama administration expelled 35 Russian diplomats in retaliation for Moscow’s meddling in the US presidential election that year. Russia, in turn, ordered the United States to cut its diplomatic presence in Russia to the same level as Russia’s in America, a reduction of about 700 positions, though these included support staff.
This time, Britain’s swift response seems to have played into the hands of Putin in domestic Russian politics.
Putin has cast himself as the protector of a country besieged by outside forces. In interviews last week, he described previously undisclosed decisions he had made in tense moments during his long tenure as commander in chief.