A farmer has been seriously injured by a bull in Naike, west of Huntly tonight.

The farmer suffered serious chest injuries while working in a bullyard, after one of the bulls reportedly caused a yard gate to hit him heavily.

St John said an ambulance attended the incident at 7.11pm. The Waikato Westpac Rescue Helicopter was dispatched to the farm around 7.30pm.

The farmer was treated by St John paramedics at the scene and and flown to Waikato Hospital for further treatment, according to a Philips Search and Rescue Trust spokesperson.