Newly-released footage from inside Pike River mine "doesn't change anything", Prime Minister Bill English says.

"A lot of these issues have been considered in-depth by the royal commission. And I think that gets overlooked a bit - a royal commission was set up, families had legal representation there, they went through all this," English told Mike Hosking on Newstalk ZB.

"But, look, there are still questions the families want answered. And that's why we are proceeding with this unmanned investigation of the mine which will unfold over the next few months."

The footage, released to the families of the 29 men who died in the mining disaster, was aired on Newshub last night.

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It was shot in 2011 by a camera lowered down borehole 44, which was drilled after the explosions. The footage shows rubber hoses and wooden pallets that appear unburnt, deep in the mine next to the coalface.

Families say that contradicts the story they were told - that everything in the mine had been burnt up.

Nick Smith, acting Conservation Minister for Pike River issues, said the expert reports never claimed the entire mine was an inferno.

"There is nothing in the film released that changes anything in the technical reports. None of them claimed that every corner of the mine was burnt to a cinder," he said.

"It would only be possible for there to be fire where there was both the presence of methane, oxygen and a source of ignition."

Labour leader Andrew Little said the new footage provided a compelling reason to allow re-entry into the mine.

"I have committed to safe re-entry of Pike and we'll clear the technicalities that the Government hides behind instead of providing the leadership the families so desperately need."

The Government says there are several key aims of unmanned entry, including getting more information about the mine's drift beyond the 1600m mark. That could help ensure other mines operate safely, Smith said, and gather more information about the electrical and control stations at about the 2km mark.

Some families say the Government is dragging its feet on the unmanned entry plan, not wanting it to proceed before September's election.

The mine has not been operating since a gas explosion in 2010 killed 29 workers, whose remains have never been removed because of concerns about high methane levels.

The Government has ruled out manned re-entry on health and safety grounds. State-owned miner Solid Energy has control of the mine.

In February, police and the Government were accused by some Pike River families of holding back footage taken from a robot that entered the mine drift in March 2011. That accusation was denied.

New Zealand First leader Winston Peters has said there has been a "cover-up" at Pike River, and has said a manned entry into the mine's drift would be a bottom-line for his party in any negotiations to form a Government after September's election.