Russia's military intelligence service has led a campaign of "indiscriminate and reckless cyber attacks targeting political institutions, businesses, media and sport," the U.K.'s National Cyber Security Centre said in a statement.
Under names including Fancy Bear, Pawnstorm and Tsar Team, the agency known as the GRU was "almost certainly responsible" for a number of serious attacks on countries including the U.S., the U.K. and Russia itself, the NCSC said. Among them was the hacking of the Democratic National Committee in 2016.
"The GRU's actions are reckless and indiscriminate: they try to undermine and interfere in elections in other countries; they are even prepared to damage Russian companies and Russian citizens," U.K. Foreign Secretary Jeremy Hunt said in a statement. "Our message is clear: together with our allies, we will expose and respond to the GRU's attempts to undermine international stability."
Australian Prime Minister Scott Morrison and Foreign Minister Marise Payne joined the U.K. in condemning "malicious cyber activity" by Russia.
The NCSC said the Kremlin was ultimately responsible for the attacks, which also included the 2017 hacking of the World Anti-Doping Agency, which led to the release of athletes' medical records. In another incident that same year, BadRabbit ransomware disrupted the Kyiv metro, Odessa airport, Russia's central bank and two Russian media outlets, according to the statement.
The accusations came as Russian President Vladimir Putin denounced ex-spy Sergei Skripal as a "scumbag" and a "traitor" in response to accusations that Russia used a chemical weapon on the double agent in an attack in the U.K. in March. Putin reiterated his denial that Russia was responsible for the incident, which led to a mass expulsion of diplomats from Europe and the imposition of sanctions by the U.S.
The U.K. has accused two Russian military intelligence agents of carrying out the poisoning using a nerve-agent called Novichok smuggled in a fake Nina Ricci perfume bottle.
