Historical buildings at the former BHP Mayfield site will be torn down by the Newcastle Port Corporation to remediate the land they stand on.

The land surrounding the buildings was remediated and flattened by BHP 12 years ago but the Medical Centre, Master Mechanics Office and the Pattern Store were spared for adaptive reuse.

The buildings have stood empty and now the corporation plans to demolish them prior to a handover to a private operator under the state government's 98-year port lease.

Parts of the buildings - like the Pattern Store's sandstone from Duckenfield Park House, a Morpeth 1800s mansion - must be preserved under a Local Environment Plan heritage listing.

The Newcastle Industrial Heritage Association is asking the corporation to delay the process for further consultation.

Association president Bob Cook said many members had worked at the steelworks and wanted the buildings preserved.

"I worked at the steelworks for 36 years and it's important that the buildings remain as relics of the site's working past," he said.

An Infrastructure State Environment Planning Policy allows the corporation to demolish the buildings without public consultation.

A Newcastle Port Corporation spokesperson said the site's acquisition from Government Property NSW included a requirement that remediation work be carried out by the Hunter Development Corporation.

"Due to the remediation work needed, the buildings will have to be removed," the spokesperson said.

A heritage assessment has been carried out.