Britain will take action over the death in prison of Russian opposition leader Alexei Navalny and it is calling on other countries to do likewise, British foreign minister David Cameron said on Saturday.
"There should be consequences when appalling human rights outrages like this take place," Cameron told Sky News.
"What we do is we look at whether there are individual people that are responsible and whether there are individual actions that we can take."
Russia's prison service said that Navalny, 47, fell unconscious and died on Friday after a walk at the Arctic penal colony where he was detained. Navalny's spokeswoman Kira Yarmysh on Saturday confirmed his death, citing an official notice given to his mother, Lydumila.
Western leaders and officials have expressed outrage over the death of Navalny, the most prominent critic of Russian President Vladimir Putin. Kremlin spokesman Dmitry Peskov called the reaction unacceptable on Friday.
Russia said on Saturday that it was unacceptable for Britain to interfere in its internal affairs after London told a top embassy official that it held Russian authorities responsible for Navalny's death.
Russia said a diplomat from the embassy had been "invited" to a conversation at the Foreign Office.
The British government said on Friday it was summoning an official from the Russian embassy to make clear it held Russian authorities "fully responsible" for the death.
Cameron declined to give details about possible action and said he would raise the issue with his counterparts from Group of Seven countries and other nations at an annual meeting of defence and diplomatic officials taking place in Munich.
"We will have the discussions with them. I am clear we will be taking action and I would urge others to do the same," he said.
