A rahui is in place, after the death of a man at Christchurch's Lake Rua on Sunday

His body was retrieved by the police and dive squad the following day.

The rahui prevents anyone swimming or entering the water, and bans fishing, until Monday.

Ngai Tuahuriri spokesperson Te Marino Lenihan says a rahui is an old custom designed with the health and safety of people and waterways in mind, and is not something that's done lightly.

The man's death will be referred to the Coroner.