LONDON, May 24 — A new website that published leaked emails from several leading proponents of Britain's exit from the European Union is tied to Russian hackers, according to a Google cybersecurity official and the former head of UK foreign intelligence.

The website - titled "Very English Coop d'Etat" - says it has published private emails from former British spymaster Richard Dearlove, leading Brexit campaigner Gisela Stuart, pro-Brexit historian Robert Toombs, and other supporters of Britain's divorce from the EU, which was finalised in January 2020.

The site contends that they are part of a group of hardline pro-Brexit figures secretly calling the shots in the United Kingdom.

Reuters could not immediately verify the authenticity of the emails, but two victims of the leak today confirmed that they had been targeted by hackers and blamed the Russian government.

"I am well aware of a Russian operation against a Proton account which contained emails to and from me," said Dearlove, referring to the privacy-focused email service ProtonMail.

Dearlove, who led Britain's foreign spy service - known as MI6 - between 1999 and 2004, told Reuters the leaked material should be treated with caution given "the context of the present crisis in relations with Russia."

Toombs said in an email he and his colleagues were "aware of this Russian disinformation based on illegal hacking." He declined further comment. Stuart, who chaired Britain's Vote Leave campaign in 2016, did not return emails.

Shane Huntley, who directs Google's Threat Analysis Group, told Reuters that the "English Coop" website was linked to what the Alphabet Inc-owned company knew as "Cold River," a Russia-based hacking group.

"We're able to see that through technical indicators," Huntley said.

Huntley said that the entire operation - from Cold River's hacking attempts to publicising the leaks - had "clear technical links" between one another.

The Russian embassies in London and Washington did not return emails seeking comment.

Britain's Foreign Office, which handles media queries for MI6, declined comment. Other Brexit supporters whose emails were suspected of being disseminated on the website also did not respond to emails. — Reuters