"We have complete confidence in the UK's assessment that this attack involved a military-grade nerve agent developed by Russia," the official said. "Prime Minister [Theresa] May laid out a convincing case that concluded in just two possibilities: either the use of this nerve agent was a deliberate action by the Russian government or else it was a result of Russia's failure to declare and secure its stocks of this weapon."
Earlier in the day, Russian Foreign Ministry spokeswoman Maria Zakharova declared that the conclusions of the UK government laboratory in Porton Down had not been officially given to Russia.
On April 3, DSTL chief executive Gary Aitkenhead said they have identified the nerve agent used to poison the Skripals, but have not verified the precise source.
British Prime Minister Theresa May stated that Russia was "highly likely" behind the attack on the Skripals and the United Kingdom expelled 23 Russian diplomats.
More than two dozen countries expressed solidarity with the United Kingdom and expelled more than 150 Russian diplomats in connection with the Salisbury poisoning incident.
Russia has denied any involvement in the Skripal case. Moscow has repeatedly offered assistance to conduct a joint investigation as per international law and requests samples of the chemical substance allegedly used to poison the Skripals, but has been rejected.
Furthermore, Russian officials have continuously pointed out that the United Kingdom has not offered evidence to support the allegations it made with respect to the poisoning incident.