Manukau Mayor Len Brown is calling on the Government to step in and define the roles and functions of local boards on the Auckland Super City authority.

A proposal for large local boards in the Super City is causing anxiety among Auckland mayors and community leaders.

Auckland Mayor John Banks calls the city's new local government structure "an inspired piece of work".

The Auckland Super City will be made up of 12 wards with about 20 local boards at the grassroots democracy level.