"Anyone who was on that site was committing a criminal offence but I'm hoping people will be honest enough to realise their mistake and hand over any artefacts that they may have claimed," Dr Schmidt said.
The section was of significant importance because of the 1894 fire.
"When a building burns down it creates a snapshot in time, things drop to the ground in one layer so we can get an idea of what cutlery and bottles were in use at the time and where they come from. It's an important piece of cultural history."
Dr Schmidt said the Historic Places Trust had successfully prosecuted fossickers or developers in Auckland and Otago recently but it preferred to educate rather than prosecute. The treasure hunters have nothing to fear if they complied with the trusts' request.
"I would urge the people who removed the items to hand them over willingly."
Dr Schmidt said the trust may do its own fossicking but that would depend on what the lessee had planned for the site.
"If it is built on again it will require an Archeological Authority and any action we take would depend on what sort of building was being erected.
"For instance if it required piles we would first excavate where the piles were to driven, but ideally we just like to leave the sites undisturbed."
