The heads of the Arctic penal colony where Russian opposition figure Alexei Navalny was “detained and killed” will be banned from the UK and see their assets frozen under new measures announced by Lord David Cameron.

Britain is the first country to impose sanctions in response to the politician’s death, which has been widely blamed on the Kremlin, the Foreign Office said.

Vadim Konstantinovich Kalinin, who allegedly oversaw the brutal prison camp where Mr Navalny was kept in solitary confinement for up to two weeks at a time, is among those targeted, according to a statement from the department on Wednesday.

Five others have also been sanctioned for “activity that violates the right not to be subjected to cruel, inhuman or degrading treatment or punishment and the right to life”, the Government said.

Foreign Secretary Lord Cameron, who will later renew condemnation of Russia’s war in Ukraine when he speaks at a meeting of foreign ministers from the G20 nations in Rio, said “no one should doubt the oppressive nature” of the Russian regime.

But Conservative chairwoman of the Foreign Affairs Committee, Alicia Kearns MP, said Britain needs to “go a lot further”.

Those targeted have been identified as:

– Colonel Vadim Konstantinovich Kalinin – head of the IK-3 Arctic colony nicknamed ‘Polar Wolf’– Lieutenant Colonel Sergey Nikolaevich Korzhov – deputy head– Lieutenant Colonel Vasily Alexandrovich Vydrin – deputy head– Lieutenant Colonel Vladimir Ivanovich Pilipchik – deputy head– Lieutenant Colonel Aleksandr Vladimirovich Golyakov – deputy head– Colonel Aleksandr Valerievich Obraztsov – deputy head

Lord Cameron said: “It’s clear that the Russian authorities saw Navalny as a threat and they tried repeatedly to silence him.

“FSB operatives poisoned him with Novichok in 2020, they imprisoned him for peaceful political activities, and they sent him to an Arctic penal colony.

“No-one should doubt the oppressive nature of the Russian system.

“That’s why we’re today sanctioning the most senior prison officials responsible for his custody in the penal colony where he spent his final months.

“Those responsible for Navalny’s brutal treatment should be under no illusion – we will hold them accountable.”

Responding to the announcement, Ms Kearns said in a tweet on X: “We need to go further than this. A lot further.”

At a summit later on Wednesday, the Foreign Secretary and counterparts from other major countries will highlight what they view as an assault on international norms, ranging from Russia to the Houthi attacks in the Red Sea.

The US has promised its own “major sanctions package” on Friday in response to Mr Navalny’s death.

Lord Cameron is expected to set out the consequences Russia will face from the UK later as he also takes aim at what he sees as a litany of hypocrisy from the Kremlin over Ukraine.

His Russian counterpart, Sergei Lavrov, is expected to be among the ministers at the G20 gathering.

This week marks two years since the Russian invasion of Ukraine, and the death of Mr Navalny, which Foreign Office minister Leo Docherty has described as “murder”, has added to international outrage about the regime in Moscow.

His death deprived the Russian opposition of an influential figure less than a month before an election that is all but certain to give Mr Putin another six years in power.

The Kremlin has dismissed suggestions it is to blame.

The summit in Rio de Janeiro comes after Lord Cameron visited the Falkland Islands and Paraguay on Monday and Tuesday.

He will also head to New York for a United Nations session on Ukraine on Friday.

Mr Navalny was one of the most prominent and persistent critics of the Kremlin, remaining a thorn in Mr Putin’s side even while behind bars via scathing attacks that his associates continued to post on social media.

He had been transferred in December to the town of Kharp, in the remote Yamalo-Nenets region notorious for its long and severe winters, in a move decried by his supporters as yet another attempt to silence him.

The politician’s family has since been denied access to his body as Moscow continues to deny allegations of a cover-up.

On Wednesday, Rishi Sunak told the Commons that the UK and its allies were considering all options to respond to the death of Mr Navalny.

The Prime Minister said: “The whole House will join me in sending our deepest condolences to the family of Alexei Navalny.

“He died for a cause to which he dedicated his whole life, freedom.

“And to return home knowing that (Vladimir) Putin had already tried to have him killed was one of the most courageous acts of our time.

“Together with our allies we are considering all options to hold Russia and Putin to account and this morning we sanctioned those running the prison where Alexei Navalny’s body still lies.”