A week ago Pike receiver Pricewaterhouse Coopers reported that gas levels, “mainly carbon monoxide”, had risen to such an extent the mine was unstable.

Sealing work around the ventilation shaft has been completed since.

“It is believed this has contributed to a decrease in gas levels and it is hoped this trend will continue,” PwC said.

“However, changes in the atmospheric conditions in the area are also expected to impact on gas levels in the mine.”

Other preparations are underway to set up the equipment needed for the new portal configuration, including electrical lines and compressors.

The latest mine stabilisation effort is centred on a staged re-entry of the mine.

The first step is to place airtight steel double doors at the portal.

But there is always a possibility of more delays ahead.

“The situation is being assessed daily by Pike River mine management in consultation with the New Zealand Mines Rescue Service, gas experts and the expert panel established by the receivers,” PwC partner John Fisk said.

“Safety is our first priority and in this regard we will not allow the work in the portal to commence until we have sign off from Mines Rescue and the other experts.

“We will continue to provide weekly reports on the status of the mine to the families of the 29 men and will continue to provide updates on any further developments.”