A source at State Research Institute of organic Chemistry and Technology – also known as GosNIIOKhT – said: “The work of our enterprise is classified.
“We do not comment on media information.”
The institute has a base in Moscow and a secret laboratory in a closed town called Shikhany in Saratov region.
It is here the substance is suspected to have been made.
There is another secret production facility in Novocheboksarsk, in Chuvashia region.
In Soviet times, a Lenin award was given for the development of Novichok.
The two men accused of poisoning Alexander Litvinenko in London in 2006 today both hit out at Theresa May.
Both Andrey Lugovoy and Dmitry Kovtun have complained that Russia has been wrongly blamed for the poisoning – and say the latest case in another Western attack on Moscow.
Mr Lugovoy said: “The situation around the poisoning of Skripal is going under pre-designed templates.
“Such hasty statements by British premier Theresa May, particularly regarding a nerve agent ostensibly made in Russia, are irresponsible to say the least.
“Any chemist or physicist will tell you that to determine whether or not a particular country was involved, there have to be at least some serious tests on a serious expert level.
“When such claims are made within days, this only points to the irresponsibility of the person making them, and may attest that finding out the truth is not the goal.”
Mr Kovtun said: “Prime Minister May’s statements on Russia’s involvement in Skripal’s poisoning can only show that the incident is biased and staged.
He forecast Britain would “fully ignore” evidence in the case.
He continued: “Let’s not forget that Russia was also accused immediately following Litvinenko’s death.”