Auckland Council is leaving the door open for Ports of Auckland to reclaim more of Waitemata Harbour.

Councillors have voted against a complete reclamation ban, and are backing a study of the port's expansion options.

Institute of Architects president Pip Cheshire says extending Ferguson Wharf would be a mistake.

"That will have a significant impact on the width of the harbour and the view of Browns Island and Waiheke Island from Queens Wharf will be lost."

Pip Cheshire is urging Auckland Council not to give Ports of Auckland any kind of free reign over Waitemata Harbour.

He says it isn't clear the port needs to reclaim further space.

"The evidence suggests they create territory by reclamation and then lease it or sell it off to other operators."

The port isn't expected to reclaim any further space until the council has signed off new rules for future reclamation in the Auckland Unitary Plan.

The council won't make any final decision on those rules until next year.