LONDON, April 3. /TASS/. Experts from the British Porton Down chemical weapons research center have been unable to identify the origin of the nerve agent used to poison former Russian military intelligence (GRU) Colonel Sergei Skripal and his daughter Yulia, Sky News reported on Tuesday, citing Chief Executive of the Defense Science and Technology Laboratory (DSTL) at Porton Down Gary Aitkenhead.

"We were able to identify it as novichok, to identify that it was military-grade nerve agent," he said. "We have not identified the precise source, but we have provided the scientific info to government who have then used a number of other sources to piece together the conclusions," Aitkenhead added.

He also pointed out that "it is our job to provide the scientific evidence of what this particular nerve agent is, we identified that it is from this particular family and that it is a military-grade, but it is not our job to say where it was manufactured."

Apart from that, the British chemical weapons laboratory denied involvement in Skripals' poisoning.

When asked if the lab had developed or kept stocks of this substance, Aitkenhead said that "there is no way anything like that could have come from us or left the four walls of our facility."

Skripal saga

On March 4, Sergei Skripal, who had been convicted in Russia of spying for Great Britain and later swapped for Russian intelligence officers, and his daughter Yulia suffered the effects of an alleged nerve agent in the British city of Salisbury. Claiming that the substance used in the attack had been a Novichok-class nerve agent developed in the Soviet Union, London rushed to accuse Russia of being involved in the incident. Moscow rejected all of the United Kingdom’s accusations, saying that a program aimed at developing such a substance had existed neither in the Soviet Union nor in Russia.

However, the UK expelled 23 Russian diplomats and announced other restrictive measures against Moscow without presenting any evidence of its involvement in the incident. In retaliation to the UK’s steps, Russia expelled 23 British diplomats, closed the British consulate general in the city of St. Petersburg, while the British Council had to shut down its operations in Russia.

On March 26, in the wake of the Skripal incident, a number of EU member countries, the United States, Canada and Australia announced the expulsion of Russian diplomats. In particular, Washington expelled 60 diplomatic workers and closed the Russian consulate in Seattle.

Last week, the Russian Foreign Ministry announced retaliatory measures against counties that had expelled Russian diplomats. In particular, Moscow expelled 60 US diplomats and closed the US consulate general in the city of St. Petersburg. The United Kingdom was requested to reduce the number of its diplomatic staff in Russia so that it would match the number of Russian diplomats in Great Britain.