British military scientists can't prove that the nerve agent used to poison Sergei Skripal was made in Russia
- British military scientists identified the nerve agent used to poison ex-spy Sergei Skripal was Novichok, but have not verified where exactly it was made.
- Gary Aitkenhead, chief executive at Porton Down, told Sky News it was "not our job" to specify the source of the poison.
- However, he said that Novichok required the sophistication "only in the capabilities of a state actor."
- Theresa May accused Russia of being behind the attempted assassination three weeks ago.
British military scientists reportedly have not verified that the nerve agent used to poison ex-spy Sergei Skripal was made in Russia - but said it was "only in the capabilities of a state actor."
Gary Aitkenhead, chief executive at Porton Down, the UK Ministry of Defence's science lab, told Sky News on Tuesday that investigators have identified the poison to be military-grade Novichok, which was designed in Russia during the Cold War, but "have not verified the precise source" of it.
He noted that Porton Down was responsible for identifying the nerve agent and providing scientific information to the government, but not for concluding where the poison was made.
He said: "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."
However, Aitkenhead added that Novichok required "extremely sophisticated methods to create, something only in the capabilities of a state actor."
Theresa May accused Russia of being involved in the attempted assassination three weeks ago.
"Either this was a direct act by the Russian state against our country, or the Russian government lost control of its potentially catastrophically damaging nerve agent and allowed it to get into the hands of others," she said.
Labour leader Jeremy Corbyn said at the time that there was insufficient evidence to conclude that Russia was culpable.
However, more than 20 other countries have agreed with May's assessment, and expelled more than 100 Russian diplomats from their countries in a show of solidarity.
Russia, meanwhile, has denied all responsibility of the attack.