A Russian television journalist was punched in the face live on air Wednesday as he reported on raucous annual celebrations by paratroopers in Moscow.

Nikita Razvozzhayev, a correspondent with the pro-Kremlin NTV channel, was extolling the professionalism of Russia's airborne forces when a bearded man staggered up to the presenter and began an expletive-laden rant about invading Ukraine.

When the reporter asked him to be quiet, the man then punched the journalist hard in the face forcing him to stop his broadcast.

A still image shows reporter Nikita Razvozzhayev being struck during a live TV broadcast. (Supplied)

"If you talk to me like that you'll... get it," the man screamed.

The incident in Moscow's famed Gorky Park -- which left the anchor back in the studio stunned -- quickly went viral in Russia with over 400,000 people viewing it on NTV's website.

Law enforcement officers detained the 32-year-old assailant and opened a criminal probe into the assault, NTV reported.

The annual paratrooper holiday regularly brings drunken bedlam to city streets and parks around Russia as former and current members of the elite units cut loose.

Police said that the attacker -- identified as a Russian nationalist Dmitry Orlov -- has never served in the paratroopers.