LONDON: British Foreign Secretary Boris Johnson said on Friday that it was overwhelmingly likely that Russian President Vladimir Putin himself made the decision to use a military-grade nerve toxin to strike down a former Russian agent on English soil.

?We have nothing against the Russians themselves. There is to be no Russophobia as a result of what is happening,? Johnson told reporters at the Battle of Britain bunker from which World War Two fighter operations were controlled.

?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 the UK, on the streets of Europe for the first time since the Second World War,? Johnson said.

Prime Minister Theresa May said on Wednesday that the Russian state was culpable for the attempted murder of Sergei Skripal, a former double agent who betrayed dozens of spies of Britain?s MI6 foreign intelligence service, and his daughter.

May said that it was tragic that Putin, who is likely to coast to a fourth term in a Sunday presidential election, had chosen to act in such a way.

Soon after Johnson?s comments were reported, the Kremlin said accusations that President Putin was involved in the nerve agent attack were shocking, TASS news agency reported.

?Any reference or mention of our president in this regard is a shocking and unforgivable breach of diplomatic rules of decent behavior,? Kremlin spokesman Dmitry Peskov said, according to the agency.

Russia has denied any involvement, cast Britain as a post-colonial power unsettled by Brexit, and even suggested London fabricated the attack in an attempt to whip up anti-Russian hysteria.

Relations between Britain and Russia have been strained since the murder of ex-KGB agent Alexander Litvinenko with radioactive polonium-210 in London in 2006, a killing which a British inquiry said was probably approved by Putin.

The Kremlin has repeatedly denied any involvement in the killing.