Few changes have been made to the underground mining industry since two deaths in 2006 despite a review two years ago outlining ways to improve health and safety systems.

After two coal miners were killed on the West Coast in 2006 - one drowned and the other was killed by a rockfall - the Department of Labour reviewed the legislative and regulatory framework for underground mines.

Its report, released in 2008, raised several areas for possible increased regulation, including inspectors who would be elected by unions to check on the safety of a mines where workers raised concern.

Workers and union submissions said check inspectors would be the "single most effective solution for improving health and safety in underground mines".

That idea was opposed by mining companies which said it would create a confrontational management style.

Other issues raised were the need for safety regimes to be signed off by the Department of Labour and for areas of increased regulation around health and safety.

The main change was to increase the level of qualifications required by managers in small mines. That is expected to be in place by the new year.

Labour Minister Kate Wilkinson said that change applied to small mines, so while the Pike River event was a tragedy there was not much relevance. The idea of having check inspectors had been discounted based on Department of Labour and international advice, she said.

Check inspectors operate in at least one Australian state.

In their submission on the report in 2008, Pike River Coal said check inspectors were "totally inappropriate and not required".

"We believe that under such a regime there is a very high likelihood of abuse of such a position which will eventually ensure that health and safety will fail in that workplace."

Interpersonal conflict and potential personal grievance claims could result, its submission said adding that check inspectors were at odds with appointed mining officials.

But Peter Whittall, now Pike River Coal chief executive, warned the department that its underground mining regulations were inadequate, there were too few mines inspectors, and they had inadequate resources.

In a submission released to NZPA yesterday, Mr Whittall said safety regulations under the Government's coal mining legislation were "inadequate in some critical areas".

"Current mining regulations ... are in need of complete review and revision," he said. At the time Mr Whittall was general manager developing the Pike River mine.