Police in Moscow police say an off-duty officer has been injured after a World War II-era land mine exploded.

The police lieutenant required hospital treatment after finding the mine on the side of a motorway.

Police said the officer sustained injuries after it exploded.

A passerby on the highway saw the injured officer and stopped to help.

The RIA Novosti news agency reported earlier on Saturday that a man was injured along the highway after picking up an undetonated explosive device, resulting in injuries to his hands and face.

Moscow police haven't yet commented on the specifics of the officer's injuries.