as far back as 2013, according to the security chief.
His claims were revealed in a letter to NATO Secretary General Jens Stoltenberg setting out the government's claims that Russian Federation is the only possible culprit for the attack on the Skripals. He reiterated Russia's dismay over the British government's refusal to allow Russian diplomats access to Skripal and his daughter Yulia, who was also poisoned, saying that from Moscow's point of view, the two Russian nationals appear to have been abducted by the British authorities.
It was the first incident of a nerve agent being deployed in Europe since World War II.
"Mr. Skripal and his daughter were poisoned with a military-grade nerve agent of a type developed by Russian Federation", specifically from the Novichok group, British Prime Minister Theresa May said after the incident, based on an assessment by British experts.
He said: "A combination of credible open-source reporting and intelligence shows that in the 1980s the Soviet Union developed a new class of "fourth generation" nerve agents, known as Novichoks".
"This programme subsequently included investigation of ways of delivering nerve agents, including by application to door handles".
The UK released the intelligence on Friday linking Russian Federation to the attack on the former double agent and his daughter.
Regarding the Skripals themselves, Sedwill claims that email accounts belonging to Yulia Skripal were targeted by Russian intelligence agents in 2013, "indicating Russian intelligence service interest in the Skripals".
Russia's ambassador to the United Kingdom, Alexander Yakovenko, dismissed the charges Friday as unfounded and untrue.
Calling on North Atlantic Treaty Organisation to take action, he concluded: "I know that North Atlantic Treaty Organisation will remain seized of the need to confront the increasingly aggressive pattern of Russian Federation behaviour of which the attack in Salisbury was an acute and recent example".
The OPCW did not explicitly name Novichok in its published summary, say where the poison may have come from or assign blame for the attack. It insists that the nerve agent used on the Skripals could easily have been manufactured in any of the other countries that have advanced chemical research programs.
The chemical weapon used in Salisbury was of "high purity", the watchdog said.
Also Friday, Russian Foreign Minister Sergey Lavrov responded to an global chemical weapons watchdog's report on the poisoning.
"It is highly likely that Novichoks were developed to prevent detection by the West and to circumvent worldwide weapons controls".
"Normally, you don't worry about some impurities because they don't get in the way of the major task that you're using the chemical for, which is to poison someone".
Her father remains hospitalized but is no longer in critical condition.