Two Russian FSB agents arrested as part of a treason and illegal hacking investigation allegedly passed confidential information to the CIA, sources close to the investigation have told Interfax. Sergei Mikhailov, a cyber-security specialist at the Russian domestic intelligence agency, was arrested in December 2016, according to multiple Russian media reports.

Ruslan Stoyanov, the head of investigations at cybersecurity firm Kaspersky Lab and Mikhailov's deputy, Dmitry Dokuchaev, were also arrested.

An official told Interfax that four people in total had been charged as part of the investigation, and a further eight were suspected of working as accomplices. Some are being investigated for treason and others for separate hacking offences, according to the report.

Mikhailov and Dokuchaev are both accused of "breaking their oath and working with the CIA", according to the source.

Independent Russian newspaper Novaya Gazeta reported that Mikhailov is suspected of leaking information to US intelligence about King Servers, a hosting platform owned by Russian citizen Vladimir Fomenko.

The servers were allegedly used as a platform for cyber-attacks on election computer systems in the run-up to the 2016 US presidential election.

Russia has been accused by multiple US intelligence agencies of hacking the election in order to boost the candidacy of Donald Trump, who, after his election on 5 November, declared his desire for closer Russia-US ties.

Mikhailov also has ties to Shaltai-Boltai, a hacking collective that has published hacked emails of Russian officials and business leaders, according to Tsargrad TV, a Russian news site owned by a Kremlin-loyal businessman.