Evidence of further human remains has been discovered inside Pike River Mine, where 29 men died after explosions ripped through the coal mine 11 years ago.
Police also hope drilling an additional borehole in the new year will provide evidence of what caused the first explosion.
Imagery work from a new borehole has captured evidence of human remains inside the mine, 50km northeast of Greymouth on the South Island's West Coast, police say.
Families of the men - no bodies have been recovered since the November 2010 disaster - have been told.
The images, which have been reviewed by pathologists, show two sets of probable human remains and one set of possible human remains, Detective Superintendent Peter Read said.
"The images were taken in the area of One West Mains, which is the western extremities of the mine workings. It is believed that five men were working in this area."
He said the imagery is of "far, far better" quality than previous images, thanks to new camera equipment.
"A lot of boreholes were drilled a decade ago but the imagery was very poor. You couldn't see more than 5 metres but you can now see up to 30, and there's more light.
"It's been 11 years of searching to find out what's happened in the mine. We as police officers are going to do everything to ... get answers for next of kin.
"It's imperative we do everything possible in our power to actually find those answers."
Sonya Rockhouse lost her son Ben in the Pike River Mine disaster. She said the discovery means a lot to her.
Rockhouse said she cried when she was told about it.
"I was in a bit of shock, even though I knew it was possible."
She said the discovery makes years of campaigning for more information worth it.
Rockhouse said none of what's happening at the moment would've happened if they hadn't done it.
"It's all been worthwhile, that's for sure."
The discovery follows another of human remains last month.
In that instance "two bodies with the possibility of a third" were spotted in images from boreholes, Read said.
Last month's images, also reviewed by a pathologist, were in an area police knew to be where six or eight men were when the disaster occurred.
The bodies were in the "furthest part of the mine from the entrance", which meant police wouldn't be able to recover them, Read said last month.
None of the remains seen in the mine have been identified.
Out of respect for the families, and because they were obtained as part of an ongoing criminal investigation, the images are not be released at this time.
Both sets of images were taken since the additional borehole drilling programme started in June, Read said.
Additional bore hole
That programme was to end two days ago, but police - who are investigating the disaster - last week received approval for the drilling of an additional borehole at the mine.
This means the drilling programme will continue into the New Year.
"The new bore hols is going to be borehole 64 at the bottom of Return Road...where they were extracting coal from."
However, Read said it will be the last borehole to be drilled at the mine before the programme ends.
"The extra bore hole gives us valuable information in regards to the first explosion and what initiated that, and hopefully, how it developed.
"We're very interested in that area to see what, if anything, transpired after the roof collapse in the goaf."
Read said it was where ventilation flow was maintained throughout the mine. Police want to see if that's "still intact".
"That will give our experts evidence on what actually transpired."
Police asked for another borehole after geotechnical engineers identified a suitable additional drilling site early this month.
Read was thinking of the killed miners' families and loved ones as they processed the latest discovery, he said.
"The search for answers over the last 11 years has been a long and painful journey for the families and my heart goes out to them."
Unlikely remains will be removed
Some Pike River families have fought for years to get authorities to find bodies in the mine but, speaking after last month's discovery of remains, Minister Responsible for Pike River Re-entry Andrew Little said while the finding was "significant" it was unlikely the remains would be removed.
Read said police won't be able to formally identify all the human remains recovered, and the purpose of the boreholes has been to gain evidence, and not to recover bodies.
The Pike River Recovery Agency earlier safely recovered the tunnel as far as the roof fall at the end of the drift in February at a cost of $51 million, more than double the original budget.
Little confirmed the Pike River agency is at the end of its budget and said advice from police and the agency point towards a recovery being "impossible".
Bernie Monk, whose son Michael died in the disaster, said after last month's discovery of remains the Government, WorkSafe and police had let the families down.
"If we go right back, we were the ones who showed them the self-rescue boxes open; we were the ones who showed the bodies of the men in early 2011; we're the ones who brought in the expertise … and they've taken absolutely no notice of us."
The Royal Commission on the Pike River Coal Mine tragedy found that the "immediate cause of the first explosion was the ignition of a substantial volume of methane gas", but could only speculate on what might have triggered ignition.
Mine owner Pike River Coal Ltd hadn't completed the systems and infrastructure necessary to safely produce coal, and its health and safety systems were inadequate, the commission's report said.
WorkSafe laid charges against former Pike River boss Peter Whittall in 2013, but the case was dropped after a $3.4 million settlement was paid – a deal the Supreme Court later said was unlawful.