The Foreign Office officials of UK have summoned the Russian Embassy amid anger in Western capitals over the death of jailed opposition leader Alexei Navalny.

UK Foreign Secretary Lord Cameron said Russian President Vladimir Putin must be held accountable, as he warned that there should be “consequences” for the Moscow leader, of whom Mr Navalny was one of the most prominent and persistent critics even while behind bars, reports The Independent.

Britain has joined other western countries in condemning the Kremlin after Russia’s federal prison service said in a statement that the 47-year-old politician and anti-corruption campaigner had died.

According to the agency, he became unwell after a walk on Friday and lost consciousness.

An ambulance arrived but he died despite attempts to resuscitate him, it said.

A Foreign Office spokesperson said Mr Navalny’s death must be “investigated fully and transparently”.

They said: “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.

“We stand today with his family, friends, colleagues and supporters. Our thoughts go out to them.

“The Russian authorities saw Mr Navalny as a threat. Many Russian citizens felt he gave them a voice.

“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.”

It is understood officials were informed the Russian Ambassador was too ill to attend, with a deputy sent instead.

Bd-pratidin English/Lutful Hoque