People stand outside the portal to a colliery named Pike River Coal in New Zealand in this January 17, 2007 handout photo released to Reuters, Nov 19, 2010. [Photo/Agencies]

WELLINGTON - An explosion rocked a remote colliery in New Zealand on Friday, trapping 27 people underground, the company and local authorities said.    

The new mine, which only began shipping coal this year, is dug into the side of a mountain range in the country's rugged South Island, burrowing into a deposit that, according to one recent visitor, was relatively gaseous.      

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Two men had come out of the mine and were being treated in hospital for moderate injuries. They had told authorities that another three were making their way out.    

Police said they did not know of any deaths, as was being reported by some media.    

"There are no confirmed fatalities," a police spokeswoman told Reuters.    

Peter Whittall, chief executive of the mine's owner, Pike River Coal , said he believed 27 people, a mix of miners and external contractors, were trapped.      

"Whether they are trapped or choosing to stay underground and shelter from whatever the extent of the incident is, we don't know at this stage," Whittall told Television 3.    

The mine's main tunnel is more than two kms into a mountain range. The area is so remote that mobile-phone service is patchy.  

The company produces hard coking coal used in the steel industry and has been hit by a series of technical problems, including rock falls, which delayed the mine's development.  

The Greymouth district's deputy mayor, Doug Truman, told Reuters by phone he had visited the mine and understood the  coal deposit to be gaseous, but he stressed the safety  standards there were very high and the workers highly trained.

"It's a very high-quality coal but it's gaseous - but  they know that," Truman said.      

The company is around 30 percent owned by NZ Oil and Gas  Ltd with two Indian companies - Gujarat NRE and Saurashtra  Fuels - as substantial minority shareholders.    

The last major coal mining disaster in New Zealand was in 1967 when 19 miners were killed in an explosion at a coal mine in the same part of the country, a major coal-producing region.