Alexei Navalny: Britain and America's ambassadors to Moscow lay flowers for 'murdered' Putin critic and 'other victims of political repression in Russia' after jailed Russian opposition was found dead
Russians brave Putin's wrath to lay flowers in honour of Alexei Navalny, who was 'found dead'. One of Vladimir Putin's most vocal critic, Navalny was serving a 19-year sentence on charges of extremism.

The British and American ambassadors to Moscow have laid flowers for jailed Russian opposition leader who was found dead in prison.

Alexei Navalny, 47, fell unconscious and died on Friday after a walk at the remote Arctic penal colony where he was serving a three-decade sentence, the prison service said.

His sudden death was a crushing blow to many Russians, who had pinned their hopes for the future on President Vladimir Putin's fiercest foe.

Mourners have left hundreds of flowers at the Solovetsky Stone monument in Moscow, photographs have revealed, with US ambassador Lynne Tracy and Britain's Nigel Casey among those seen paying their respects.

More than 400 people have been detained in Russia while paying tribute to Navalny, who had remained vocal in his unrelenting criticism of the Kremlin even after surviving a nerve agent poisoning and receiving multiple prison terms.

There are still few details of why he died, but prison authorities have said he suffered 'sudden death syndrome'. However, Navalny's allies and many world leaders have blamed his death on Putin and his government.