The Russian security council deputy head, Dmitry Medvedev, has described the editors of the Times newspaper in Britain as “legitimate military targets” in response to the newspaper’s coverage of the assassination of a Russian general.

Medvedev’s vitriolic comments on Wednesday followed a Times editorial in which the newspaper described the assassination of Lt Gen Igor Kirillov as “a legitimate act of defence” by Ukraine, which has claimed responsibility for the killing.

Kirillov, head of the military’s chemical, biological and radiological weapons unit, was killed along with his assistant when a device attached to an escooter exploded as the two men left a building in a residential area in south-east Moscow on Tuesday morning. Kirillov is the most senior Russian military official to be killed in an assassination away from the frontlines since the start of the Kremlin’s offensive in Ukraine nearly three years ago.

“Those who carry out crimes against Russia … always have accomplices. They too are now legitimate military targets. This category could also include the miserable jackals from The Times who cowardly hid behind their editorial. That means the entire leadership of the publication,” Medvedev, who served as Russia’s president between 2008 and 2012, wrote on his Telegram channel.

In a thinly veiled threat, the hawkish former president added that journalists at the Times should “be careful” as “anything goes in London”.

Responding to Medvedev’s post, the UK foreign secretary, David Lammy, wrote on X that his “gangster threat against Times journalists smacks of desperation”.

“Our newspapers represent the best of British values: freedom, democracy and independent thinking,” Lammy wrote alongside a picture of himself reading the Times.

Asked about Medvedev’s comments, the UK prime minister’s official spokesperson said they were “simply the latest in a series of desperate rhetoric coming from Putin’s government.”

The spokesperson added: “Unlike in Russia, a free press is a cornerstone of our democracy and we take any threats made by Russia incredibly seriously.”

Medvedev, who cast himself as a liberal reformer promising modernisation and democratisation upon becoming president in 2008, has reinvented himself as one of Russia’s most vocal pro-war figures.

He is now best known for his fiery anti-western tirades on Telegram, which some observers see as a desperate attempt to maintain political relevance.

Still, Medvedev remains a prominent Putin confidant and recently travelled to Beijing for talks with Chinese leader Xi Jinping, one of Russia’s key allies.

In the same post on Wednesday, Medvedev also threatened Nato officials assisting Ukraine.

“There’s a whole legion of them. There’s not even enough space to list them, but all these individuals can and should be considered legitimate military targets for the Russian state. And for all Russian patriots for that matter,” he wrote.

Since the start of Russia’s full-scale invasion, Moscow has banned dozens of British journalists, media representatives and senior UK politicians from entering the country.