In a nine minute video on Monday, 47-year-old Navalnaya, said: "Three days ago, Vladimir Putin killed my husband Alexei Navalny, the father of my children and took away the most important thing I had. The person who was closest to me and whom I loved most.

During an interview, Navalnaya, an economist who had left her job for raising her kids, said: "When you are not a politician but you see the darkest things against your family then, of course, it radicalises you."

She said that the most important thing "we can do for Alexei and for ourselves is to continue to fight more desperately, more fiercely than before."

She also accused the authorities of hiding her husband's body. Authorities told Navalny's mother that his body will not be handed over to family for two weeks as they are conducting chemical analysis, Navalny's spokewoman Kira Yarmysh was quoted as saying by BBC.

Navalny, who has been Putin's most prolific critic for over a decade, was confirmed dead by the opposition on Saturday.

Earlier, the Western leaders, including US President Joe Biden have blamed Puting for Navalny's death, which Kremlin spokesman Dmitry Peskov said were "arrogant" and "unacceptable".