An off-duty police officer has been stabbed after intervening in a dispute outside a western Sydney community hall.

Emergency workers were called to the scene just before 11pm yesterday to find a 36-year-old man with a torso wound at Chopin Close, Bonnyrigg Heights.

Police believe the off duty officer was intervening in a fight outside the hall when he was attacked.

He was taken to hospital in a serious but stable condition and has underwent surgery.

A man has been arrested and a weapon seized. Police looking for two others.