British Foreign Secretary Boris Johnson has said that it was “overwhelmingly likely” that Russian President Vladimir Putin ordered the use of a nerve gas agent against former spy Sergei Skripal in the city of Salisbury, AP reported on Friday.

United Kingdom Prime Minister Theresa May had said that the Kremlin, was “highly likely” to be behind the attack. However, Johnson went further, blaming Putin directly on Friday. “Our quarrel is with Putin’s Kremlin, and with his decision, and we think it overwhelmingly likely that it was his decision to direct the use of a nerve agent on the streets of Britain, on the streets of Europe, for the first time since World War II,” the foreign secretary said.

On Thursday, Johnson had claimed that Russia had deliberately chosen to attack Skripal to send a warning to Putin’s opponents, The Guardian reported.

However, the Kremlin denounced Johnson’s claim that Putin ordered the attack. Putin’s spokesperson Dmitry Peskov called it a “shocking and inexcusable breach of diplomatic propriety”. “We have repeatedly said that Russia has no relation to that [the attack],” he added.

The events so far

Skripal and his daughter Yulia were found unconscious on a bench outside the Maltings shopping centre in Salisbury. Both of them, and a police officer who first responded to them, are said to be in serious condition in hospital. Police said the substance that rendered them critically ill was a nerve agent.

On Wednesday, May ordered 23 Russian diplomats to leave the country after her ultimatum to Russia to respond to allegations about the attack expired. On Thursday, the United Kingdom, the United States, France and Germany issued a joint statement holding Russia responsible for the poisoning.