Video: Pike River victim's father watches robot video

"We are going to peel back the litany of lies and expose this for what it is."

That was the reaction of Dean Dunbar after seeing the robot video taken inside Pike River, but kept from the families up until now.

Mr Dunbar's son Joseph Dunbar was killed inside the mine - one day after his 17th birthday.

The footage is six years old, date-stamped March 15, 2011 - three months after the final explosion, and held by police ever since.

The Government, authorities and the mine's controllers have always maintained it's too dangerous to enter, which Mr Dunbar rejects.

"They created a situation of absolute danger; they made it look and sound explosive. It's not."

Mr Dunbar allowed Newshub to film him watching the video, and describes the two mines rescue workers repairing the robot - which overheats and lets off smoke or steam, without causing a fire.

Watch Dean Dunbar's reaction to the video.