Auckland Council has five guns that are now banned following the Christchurch mosque attacks.
The council conducted an audit of its firearms after changes to gun control legislation.
Customer and community services director Ian Maxwell says the audit found it has five shotguns, which are now prohibited because their magazines contain one more round than is now permitted.
He says the council has spoken to police and is waiting for more instructions about how and when the firearms can be handed over.
Maxwell says police have asked that the five firearms are securely stored in a locked safe with "Do not use" labels on each of them.