No criminal charges will be laid by New Zealand police against individuals involved in the Pike River mine disaster, after an investigation concluded there was not enough evidence to prove manslaughter.
The families of the 29 men killed in the explosion at the Pike River mine on November 19, 2010 were informed of the outcome of the two-and-a-half year police investigation at a meeting in Greymouth on the South Island's west coast on Wednesday night.
Police say there is not enough evidence to link any individuals to specific events leading to the explosion and therefore manslaughter charges had to be ruled out.
Detective Superintendent Peter Read said he knew the families of the victims would be disappointed with the outcome.
"This has been a very difficult decision and not one taken lightly," he said.
He said the investigation had been one of the most complex ever undertaken by New Zealand police, involving interviews with 284 people and 34 million pages of documentation.
Police said there was enough evidence to charge individuals with criminal nuisance, but given the ongoing investigations by Ministry of Business, Innovation and Employment(MBIE), those charges would raise double jeopardy issues.
Any penalties arising from police charges would be unlikely to supersede those imposed under MBIE prosecutions, police said.
Police are not ruling out reopening the investigation should access to the mine be gained in the future.
Access would allow a scene examination.
"However, I stress there is no certainty that this would produce any new relevant information," Det Sup Read said.
"Even if new information was identified, there is no guarantee that it would lead to a future prosecution."
Earlier in July, Pike River Coal was ordered to pay $NZ110,000 ($A94,840) to each of the families of the 29 victims killed in the explosion.
The company was also fined $NZ760,000 for nine health and safety charges.
Last month, a judge ruled former Pike River Coal boss Peter Whittall could be tried in Wellington, rather than in Greymouth, on 12 health and safety breaches.