Alexei Navalny’s wife has urged world leaders to hold Vladimir Putin responsible for her husband’s death in an emotional speech just hours after hearing the news.

Yulia Navalnaya said she was only able to take to the stage at the Munich Security Conference because she thought of what her husband would do in her place.

Mrs Navalnaya, who received a standing ovation after the short address, wore a stoical expression as she gave the impromptu speech, which was not listed on the original conference schedule.

She received a standing ovation from the audience as she gave a moving speech at the Munich Security Conference on Friday.

She said: “You will have heard about the horrific news. I thought for a while should I stand here before you or go back to my children. I wondered what Alexei would have done in my place. I’m sure he would have been standing here on this stage.”

She added: “I don’t know if we should believe the terrible news, the news we get only from official media because for many years, we have been in this situation, we cannot believe Putin and his government, they are lying constantly.”

Mrs Navalnaya, 47, married Alexei in 2000 and the couple have two children. She has been described as the “First Lady” of the Russian opposition due to her own outspoken political activism and enduring support for Alexei after his imprisonment.

In her 10-minute speech, she said: “They [Navalny’s killers] will be brought to justice, this day will come soon. We should fight this horrific regime...this regime and Vladimir Putin should be personally held responsible for all the atrocities they have committed in our country in these last years.”

It also emerged on Friday that Mr Navalny had sent a poignant Valentine’s Day message to his wife from prison. “Baby, everything is like a song with you: between us there are cities, the take-off lights of airfields, blue snowstorms and thousands of kilometres,” he said in the message.

“But I feel that you are near every second, and I love you more and more.”