The body of a man thought to be in his 40s or 50s has washed up on New Brighton beach in Christchurch.

He was found by a member of the public near the beach pier at around 7am.

Christchurch Police are treating the discovery as suspicious.

Senior Sergeant Craig Scott said they want to hear from anyone who may have seen any unusual behaviour in the past few days.

He described the man as a male Caucasian, between 40 and 50 years of age, with grey hair that is bald on top.

He said fingerprints are being taken, and there'll be a postmortem tomorrow.