Dunedin Mayor Dave Cull has welcomed support from his Auckland counterpart, as southern councils lobby for changes to earthquake-prone buildings legislation.

Auckland Mayor Len Brown has added his voice to the concerns, adding his name to a letter to the Local Government and Environment Select Committee considering the issue.

Fears have been raised in Dunedin a tough new approach to earthquake-prone buildings risks derailing progress on the city's heritage buildings.

Brown says Auckland and southern councils have identified common issues he believes need serious consideration by the select committee.

Cull says he welcomes the support from Auckland.