Moscow: In an extraordinary public outburst, the chief of the Russia's National Guard and President Vladimir Putin's former bodyguard has challenged opposition leader Alexei Navalny to a duel.

"I'm simply challenging you to a fight: to a ring, to a tatami, anywhere where I promise I will make a good juicy beef steak of you," Zolotov said, seated at the desk and shaking his fist.

Viktor Zolotov recorded an emotional seven-minute speech, posted on the National Guard's YouTube channel on Tuesday, attacking Navalny for his investigation into large-scale corruption at the National Guard. Zolotov admitted "shortcomings in terms of corruption" in his governmental agency but rejected Navalny's claim that he personally profited from the shady deals.

Navalny, Russia's most popular opposition leader, is currently in jail serving a 30-day sentence for organising an unsanctioned public protest. Last month he published an investigation alleging that at least $US29 million ($40 million) had been stolen in procurement contracts for the National Guard.