An elderly man has been left with severe injuries after he was allegedly injured by a lawnmower during a neighbour dispute on the state's north coast on Saturday morning.

The man, aged 81, and his 72-year-old neighrbour were allegedly involved in a fight about 9.30am on Crestwood Drive, Port Macquarie.

The altercation followed a dispute over a patch of lawn located between the two men's houses, police understand.

Police allege a "large knife" and a lawnmower were used during the fight.

The 81-year-old suffered "severe hand and leg injuries" caused by the lawnmower, as well as injuries to his torso, police say.