The chief executive of Britain's Porton Down defense laboratory says his scientists have not verified the "precise source" of the nerve agent used to poison the former Russian double agent Sergei Skripal and his daughter -- explaining that it was not the task of his laboratory to do so.
Gary Aitkenhead reiterated in an April 3 interview with Sky News that the attack with a highly toxic Novichok nerve agent was "probably only within the capabilities of a state actor."
He also said there is "no way" the nerve agent could have come from the high-security Porton Down facility, as the Kremlin has suggested.
Aitkenhead explained to Sky News that it is Porton Down's job to "provide the scientific evidence that identifies what the particular nerve agent is...but it's not our job to say where that was actually manufactured."
He also said the Porton Down laboratory "provided the scientific information to the government who have then used a number of other sources to piece together the conclusions that they have come to."
Based on that information, the British government has said that the Russian state must have been behind the attack with a Soviet-developed nerve agent against Skripal and his daughter Yulia on March 4 in Salisbury.
Russia denies responsibility and has suggested the poison may have come from Britain.
Aitkenhead's remarks came a day before the Organization for the Prohibition of Chemical Weapons (OPCW) watchdog was due to discuss Britain's allegations against Russia over the poisoning.
The OPCW said on April 3 that Russia had requested a meeting of its executive council to discuss the case.
Meanwhile, Britain's Foreign Ministry on April 3 accused Russia of calling the meeting as a "diversionary tactic" to undermine the investigation into the poisoning.
"This Russian initiative is yet again another diversionary tactic, intended to undermine the work of the OPCW in reaching a conclusion," the ministry said in a statement.
Britain, the United States, and two dozen other countries have expelled more than 150 Russian diplomats in response to the poisoning, and Moscow responded in kind.
British authorities have invited OPCW experts to take chemical samples from Salisbury for analysis.
Last week, Russia sent a list of questions to the OPCW’s secretariat regarding the information provided by London to the agency, the composition of the expert group that visited Britain, and other issues.
Russian news agencies quoted the OPCW’s press service as saying that the organization anticipates sending its answers to Russia by the end of April 3.
On April 2, Russia’s envoy to the OPCW said in televised remarks that Moscow won't accept the agency's conclusions without Russian involvement.
Meanwhile, Russian Foreign Minister Sergei Lavrov accused the United States and Britain of spreading "lies and disinformation" about the poisoning.
And Russian Foreign Minister Aleksandr Grushko on April 3 said the Skripal case was a “provocation” by London aimed at further escalating tensions between Russia and the West.
British officials have previously rejected similar Russian allegations.
Sergei Skripal remains hospitalized in critical condition, while his daughter Yulia has partially recovered.
Skripal was a colonel in Russia’s military intelligence agency until he was arrested and charged with spying for Britain. He was released in a 2010 spy swap involving the United States and he moved to Britain.