Police are investigating an assault which happened in the early hours of Tuesday in Whangamata.

Police said a 22-year-old man was punched, knocked to the ground and had personal items stolen about 1.30am after he intervened to help a man who was being attacked by two other men near the intersection of Ocean Road and Barbara Avenue, Whangamata.

Detective Sergeant Andrew Mortimore says police would like to identify the man who was first attacked as they believe he has vital information that will assist the investigation.

Anyone who can identify the victim of the first attack or has any other information about the incident is asked to contact the Whangamata Police at (07) 865 0300 or anonymously via Crime stoppers on 0800 555 111.