Footage has emerged of an Indian policeman's hand being lopped off in a terrifying sword attack as officers stood at a coronavirus road checkpoint.

Harjit Singh, an assistant sub inspector with the Punjab Police, was patrolling outside a vegetable market in Patiala when seven men belonging to the Nihang Sikh warrior sect turned violent.

Footage shows a truck ramming through the barricades before the warriors leap from their vehicle and attack with traditional Sikh blades.

Singh's left hand is cut from his wrist and he can be seen writhing on the floor in agony, screaming as he tries to stem the flow of blood with a handkerchief.