LONDON: The British government said late Friday it had summoned diplomats from the Russian embassy “to make clear that we hold the Russian authorities fully responsible” for the death of Kremlin critic Alexei Navalny.

Russian officials said Navalny, 47, had died on Friday in an Arctic prison, a month before an election poised to extend President Vladimir Putin’s hold on power.

“In recent years, the authorities imprisoned him on fabricated charges, poisoned him with a banned nerve agent, and sent him to an Arctic penal colony.

“No one should doubt the brutal nature of the Russian system,” a Foreign Office spokesperson said.

Jailed Russian opposition leader Navalny is dead: prison service

The Foreign Office “summoned the Russian embassy to make clear that we hold the Russian authorities fully responsible”.

“Alexei Navalny dedicated his life to exposing the corruption of the Russian system, calling for free and open politics, and holding the Kremlin to account,” the spokesperson said.

Earlier Friday, British Foreign Secretary David Cameron said Putin “should be accountable for what has happened” and paid tribute to Navalny’s courage.

Supporters of Navalny turned out across Europe and in the United States on Friday evening to pay tribute to the man widely acknowledged as Russia’s main opposition figure, even when he was behind bars.

In London, dozens of people gathered in front of the Russian embassy carrying signs in English and Russian saying: “Stop Putin”, “Assassins” and “We are Navalny”.