Ongoing safety concerns have again delayed entry into the Pike River coal mine.
The plan to re-enter the mine was put forward and approved late last year by the current mine owner Solid Energy, and approved by the New Zealand Government the following month.
It was built as a staged re-entry plan.
Stage one saw workers plug the top 50 to 60 metres of the 100 metre deep ventilation shaft with around 700 cubic metres of concrete to allow for full control of the mine's atmosphere.
Stage two consisted of drilling new boreholes into the top of the main tunnel, inserting cameras to check tunnels where a second plug could be placed and then put expanding foam via borehole into the tunnel.
This formed a plug around 2.3 km into the mine and 40 metres on the portal side of the rock fall.
After this recovery teams will pumped nitrogen into the tunnel between the plug and the rock fall to prevent fresh air for entering the closed off sections of the mine, which reduced the risk of fires re-igniting within the tunnels.
Once ventilation was complete stage three would see the teams finally enter the mine.
According to Bernie Monk, a spokesperson for the families of the dead miners, the plans for re-entry has been pushed back by another month, Stuff.co.nz reports.
“We were a wee bit disappointed because we were aiming for the end of April for re-entry," he said.
"We haven't seen a date or anything, but the latest plan for re-entry is mid-June."
However he went on to say that while families were frustrated by the delays, they understood Solid Energy required additional time to ensure a safe re-entry plan.
"Safety is the top priority," he said.
"We've got to make sure that everything goes right," he said.
"The rush is not the top priority, but getting it right is the top priority."
Changes on Solid’s board have also slowed down the process.
Clifford was previously the general manager at Ulan, in New South Wales, and has spent more than two decades working coal mining around the globe.
He has also worked for Anglo American and BHP.
"That holds us up a bit because [new members] have to be brought up to speed on every aspect, because what happens will come back on them."