Online activity by Russian bots, trolls and automated accounts has increased by 4,000% in the days and weeks following the Salisbury poisoning and suspected chemical attack in Syria.
Government analysis has identified "Kremlin inspired" accounts that have repeatedly posted messages to "spread disinformation and distort the truth" – described by Prime Minister Theresa May as "part of a wider effort to undermine the international system".
One Twitter account, @Partisangirl, posted more than 2,300 tweets in less than a fortnight – an average of 200 posts a day.
It's estimated those tweets reached around 62 million people.
The research, by Whitehall officials, found that the many of the accounts commented on both events in Salisbury and Syria.
Posts included support for articles claiming the poison used on the streets of Salisbury was never produced in Russia and attempts to spread the theory that Porton Down manufactured the chemical agents used in Syria.
Separately, government social media experts have documented more than 45,000 posts propagating disinformation narratives in the two weeks since the Syria attack on 7 April, with a potential reach of around 20 million social media users.
Mrs May visited the National Cyber Security Centre (NCSC) in London on the fringes of the CHOGM summit, along with her Australian, New Zealand and Canadian counterparts. The four nations are part of the 'Five Eyes' intelligence sharing relationship, along with the United States.
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They were briefed by officials from GCHQ, the NCSC and the UK's Joint Intelligence Committee on the current threat picture, including the cyber threat posed by Russia.
Speaking after the briefing, the PM said: "This disinformation campaign is not just aimed at social media and the UK – it is intended to undermine the actual institutions and processes of the rules based system, such as the Organisation for the Prevention of Chemical Weapons. We must do all we can at every turn to challenge this."