The total recovery bill could be in the tens of millions, including costs for the GAG jet engine used to inert the mine, which is very expensive to operate.

Assistant commissioner specialist operations Grant Nicholls said the police would consider costs incurred by suppliers that contributed to the emergency response and recovery effort.

"While we are in a handover phase with the receivers, the mining company and other agencies, we are still continuing to coordinate efforts to get the mine into a safe state," he said.

"We are continuing to meet costs associated with operating the GAG unit and have arranged for the nitrogen generator unit to be dispatched from Australia.

"We will also consider other costs as they come forward, and make decisions about whether they relate to the search and recovery operation, or to other aspects of operating the mine.

"Where they are clearly contributing to the search and recovery operation, we have undertaken that we will meet those costs.

"The meeting of any other costs relating to activities at the mine or the mining company is something which will need to be considered by the receivers."

Despite the costs, Australian and NZ mines and rescue services have provided staff and equipment free of charge.

Pike receivers PricewaterhouseCoopers must authorise any company payments which exceed $NZ5000.

Pike senior management is only allowed to make payments under this amount.