The Labour leader said that Mr Johnson has "serious questions" to answer after saying in an interview a fortnight ago that he had been told by Porton Down scientists that the nerve agent used in the poisoning was made in Russian Federation.
"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", Aitkenhead added.
The British authorities have blamed Russian Federation for the March 4 poisoning, with Foreign Minister Boris Johnson suggesting it was "overwhelmingly likely" that President Vladimir V. Putin had ordered the attack.
Skripal's daughter Yulia is getting better after spending three weeks in critical condition due to the nerve toxin attack at her father's home in Salisbury, the hospital where she is being treated said last Thursday.
"We need to get to the source of this to prevent it ever happening again".
His remarks came in response to the head of the laboratory where the substance found on the Skripals was tested, saying they were not yet able to prove it was made in Russian Federation.
Britain's factories report rise in production for March
It highlighted that production fell for the first time in eight months despite a marginal contraction rate. This is the eighth consecutive month that the index remained above the 50-point-mark.
Peskov said that Britain's theory on who poisoned Skripal "will not be confirmed anyway".
Asked directly how he could assert that the source of the Novichok nerve agent was Russian Federation, the Foreign Secretary replied that he had "interrogated" the scientists.
The Russian Embassy in London contacted Victoria Skripal, a relative of the victims of the Salisbury incident, saying "our diplomats share with her the information available to the Russian side on the state of health of her relatives, on efforts being made to obtain consular access for them".
The Organisation for the Prohibition of Chemical Weapons (OPCW), the world's chemical watchdog, will meet on Wednesday to discuss Britain's allegations that Russian Federation was responsible for the poisoning, according to documents released on Tuesday.
Aitkenhead flatly denied Russian claims the substance could have come from Porton Down itself.
The UK Government has consistently blamed Moscow for the Salisbury attack, prompting an increasingly bitter diplomatic rift with the Kremlin.
Make it 2 out of 3 as Villanova Buries Michigan
They lost only once all season with a full rotation: at Creighton, 89-83, not coincidentally their final defeat of the season. This one was only handsome to one team. "I think both of us are looking for guys that want to be in college", Wright said.
A senior Labour source told Sky News they thought there were grounds to believe Mr Johnson had broken the code.
But this is an extremely toxic substance and not something that you can easily give something to somebody to help them recover. The secretive facility is the centre of Britain's chemical weapons research, which dates back to the First World War.
He had been asked why the British Government believed the nerve agent came from Russian Federation.
A senior Whitehall source said the individual had been identified as a "person of interest" by intelligence agencies, and pointed to more than one person being investigated.
"There's no way that anything like that would ever have come from us or leave the four walls of our facility", he said.
The head of Porton Down laboratories has since said that they could only determine the substance used was Novichok, and not where it came from.
No mousing around as Disney offers to take Sky News
Fox, which now owns 39% of Sky, in December 2016 launched a bid to take full control of the British company. Sky now trades higher than the Comcast proposal, indicating that investors are expecting a bidding war.
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