(Reuters) - Iceland’s leaders will not attend the soccer World Cup in Russia this year as part of an international response to punish the Kremlin for a nerve agent attack on a former Russian spy in England that the British government has blamed on Moscow.

On Monday, British Prime Minister Theresa May said that more than 130 people may have been exposed to a nerve agent believed to have been used to poison ex-spy Sergei Skripal and his daughter in the English city of Salisbury on March 4.

May, welcoming the show of solidarity, said 18 countries had announced plans to expel Russian officials. Those included 14 European Union countries. In total, 100 Russian diplomats were being removed, the biggest Western expulsion of Russian diplomats since the height of the Cold War.

Russia has repeatedly denied responsibility for the nerve agent attack.

“So far, Russia’s response has been severely lacking,” the Icelandic Foreign Ministry statement said. “Russia must provide credible explanations on how a nerve agent originally produced in Soviet laboratories came to be used to attack civilians in the United Kingdom.”