The admission comes after Russia demanded the UK present “every possible element of evidence” that it was responsible for the suspected assassination attempt that has triggered a global diplomatic row and plunged Moscow’s relationship with many western nations to lows not seen since the Cold War.

The Kremlin denies any involvement in the 4 March attack, which left Mr Skripal and his daughter Yulia fighting for life, but the British government has said there was “no other plausible explanation”.

Gary Aitkenhead, chief executive of the Defence Science and Technology Laboratory near Salisbury, Wiltshire, said the nerve agent required “extremely sophisticated methods to create, something only in the capabilities of a state actor”.

But he added scientists could not say it was produced in Russia.

He said: “We were able to identify it as novichok, to identify that it was a military-grade nerve agent. “We have not identified the precise source, but we have provided the scientific info to the government who have then used a number of other sources to piece together the conclusions you have come to.”     (The Independent)

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