A Japanese mining contractor with decades of experience was too frightened to go into the Pike River mine because he was worried it would explode, the Royal Commission into the disaster will hear.
The written evidence of Masaoki Nishioka, obtained by Radio New Zealand, will be presented to the inquiry into the West Coast mine explosion next week.
The inquiry was set up to investigate what led to the disaster on November 19 last year in which 29 men were killed.
Mr Nishioka, a high pressure water mining expert with 40 years of experience, quit the mine a month before the disaster after he became too scared to go underground.
His evidence said there were serious design flaws with the water system, the methane gas removal system, and the coal faces.
Questions would be raised over why Mr Nishioka did not raise concerns with management before he left the mine, Radio New Zealand reported.