There will be “consequences” for the death of Alexei Navalny, Lord David Cameron has said, as Western capitals pinned the blame on Vladimir Putin.

Protests and gatherings took place around the world after news emerged of the death of the jailed Russian opposition leader.

In London, the Foreign Office summoned diplomats at the Russian Embassy and called for Mr Navalny’s death to be “investigated fully and transparently”.

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.

His spokeswoman confirmed his death on Saturday.

In a post on X, formerly known as Twitter, Kira Yarmysh said: “His death occurred on February 16 at 2.17 p.m. local time, according to the official message to Alexey’s mother.

“We demand that Alexey (sic) Navalny’s body be handed over to his family immediately.”

“There should be consequences,” the Foreign Secretary told broadcasters at the Munich Security Conference.

“When appalling human rights outrages like this take place, what we do is we look at whether there are individual people that are responsible and whether there are individual measures and actions we can take.

“We don’t announce them in advance, so I can’t say anymore than that.

“But that is what we will be looking at.

“Of course we have already summoned the ambassador and made clear our views about this dreadful event and the way this person was treated.”

He said he would be meeting with G7 foreign ministers at the German gathering: “I am clear that we will be taking action and I would urge others do to the same.”

Critics of Mr Putin, whose invasion of Ukraine is now approach its second anniversary, said the Russian leader had wanted to send a message both to activists inside Russia but also to the West.

His death comes less than a month before an election that will give Mr Putin another six years in power.

Ukrainian President Volodymyr Zelensky, who attended the same conference on Saturday alongside other world leaders, told those attending: “Putin kills whoever he wants.

“After the murder of Alexei Navalny, it’s absurd to perceive Putin as a supposedly legitimate head of a Russian state and he is a thug who maintains power through corruption and violence.”

“He has just yesterday he tried to send us all a clear message as the Munich Security Conference opened, Putin murdered another opposition leader.”

Mr Navalny had been jailed since January 2021, when he returned to Moscow to face certain arrest after recuperating in Germany from nerve agent poisoning he blamed on the Kremlin.

He was later convicted three times, saying each case was politically motivated, and received a sentence of 19 years for extremism.

After the last verdict, Mr Navalny said he understood he was “serving a life sentence, which is measured by the length of my life or the length of life of this regime”.

Hours after Mr Navalny’s death was reported, his widow Yulia Navalnaya made an appearance in Munich.

“I want Putin and everyone around Putin, Putin’s friends, his government to know that they will bear responsibility for what they did to our country, to my family and to my husband,” she said.

US President Joe Biden said Washington does not know exactly what happened, “but there is no doubt that the death of Navalny was a consequence of something Putin and his thugs did”.