Fears for 27 workers missing after blast rips through mine

Five workers, who were slightly injured, stumbled to the surface hours later but 27 remain unaccounted for.

Police said that shortly before the blast the electricity went out in the remote Pike River mine, which may have caused ventilation problems, contributing to a build-up of gas underground.

Rescue teams were yesterday waiting for word the mine was safe to enter.

The explosion was powerful enough to blow one driver off his machine deep in a tunnel, and a mine safety expert said gas was a possible cause, although police spokeswoman Barbara Dunn and the mine's operator stressed it was too early to say why it occurred.

Television footage showed blackened and singed trees and light smoke billowing from the top of a mountain where a 360-foot ventilation shaft emerges. A nearby hut was blown down, suggesting a powerful blast had shot up the shaft from deep in the mine.

Rescue teams and emergency workers rushed by helicopter and by road to the mine, located in remote and rugged mountains near the town of Atarau on New Zealand's South Island.

Air samples have been taken from the ventilation shaft to check whether there was a build-up of poisonous or explosive gas and if it was safe to go in.

"They're itching to get in there and start looking for other people and a bit frustrated at having to stand and wait," Ms Dunn said. "There is concern that ventilation inside the mine shaft may be compromised by the power outage."

The condition of the missing miners was not clear but the prospect that they could be alive but trapped recalls the dramatic saga of 33 Chilean mine workers who spent 69 days half a mile deep in a collapsed gold and copper mine. They were rescued last month in an event that captivated the world.

Pike River chairman John Dow said each miner carried 30 minutes of oxygen supply – enough to reach oxygen stores in the mine that he said would allow them to survive for "several days".

The coal seam at the New Zealand mine is reached through a 1.4-mile horizontal tunnel that bores into the mountain toward the seam, which lies about 200 yards beneath the surface. According to the company's website, the vertical ventilation shaft rises 354 feet from the tunnel to the surface.

Tony Kokshoorn, the mayor of nearby Greymouth, put the number of miners unaccounted for at up to 30. Peter Whittall, chief executive of mine operator Pike River Coal Ltd, said 27 people were missing – 15 miners employed by the company and 12 local contractors.

Mr Whittall said five workers had walked out of the mine two to three hours after the blast: a pair that included the machine operator who was blown off his vehicle one mile into the access tunnel. Three more came out late, one of whom had been able to make a call on his mobile phone before reaching the surface, he said.

New Zealand prime minister John Key said: "The government has told the company it will provide any support that is required. It is an Australian company that owns the mine and the Australian government has also contacted us offering their support (and) assistance," he told reporters.

Pike River Coal is a New Zealand-registered company, but its majority owners are Australian. There are also Indian shareholders.

Energy Minister Gerry Brownlee said the explosion happened at about 3.45pm local time (2.45am GMT) and the last contact with any of the miners was about half an hour later.

Two of the men who came to the surface were taken to a hospital for treatment of minor injuries.

"They're being interviewed and we're trying to determine... the full nature of the incident," Mr Whittall said.

It was not immediately clear if all of those underground were together or in separate groups.

Mine safety expert David Feickert said yesterday's blast could have been a gas explosion.

Mr Brownlee said emergency exit tunnels were built into the mine but that he didn't know if they could be accessed by the missing workers