A one-armed man is accused of a stabbing at an 18th birthday party north of Auckland during the weekend.

About 4am on Sunday police arrived at a house in James McLeod Rd, Shelly Beach, to find a man with multiple wounds to the torso and one to the head.

The 27-year-old was airlifted to Auckland City Hospital by the Westpac Rescue Helicopter with non-life-threatening injuries, and was yesterday in a stable condition.

Detective Sergeant Kevin Burke, of the Orewa CIB, did not know if the two knew each other before the party. Police were still looking for the weapon - believed to be a pocket knife or something similar, he said.

When North Shore officers - alerted by St John paramedics - arrived, they found the group of party-goers in varying degrees of intoxication, Mr Burke said.

But the party was winding down and no complaints had been made before the alleged attack.

A 31-year-old man appeared in the Waitakere District Court yesterday charged with assault and was remanded to reappear this week.

Anyone who was at the party and has not spoken to police is asked to call the Orewa station on (09) 426-4555.