The leaders of France, Germany, Britain and the United States issued a joint statement on Thursday condemning a chemical attack on a Russian former double agent in England and blaming Moscow for it.

Moscow has denied any responsibility for the attack on Sergei Skripal and his daughter Yulia. Britain has expelled 23 Russian diplomats, and Moscow is expected to retaliate.

"We, the leaders of France, Germany, the United States and the United Kingdom, abhor the attack that took place against Sergei and Yulia Skripal in Salisbury, U.K., on 4 March 2018," the statement said.