Progress had slowed in the tunnel as the miners worked carefully through the fault and an adjacent area of heavily crushed rock before hitting less fractured ground before the weekend when they were able to pick up progress rates.

Just 182m is now left of the tunnel before reaching the Brunner seam where the company plans to extract 17.6 million tonnes of coal over the next 18 years at the New Zealand mine.

“While it’s possible more fractured rock could again be found in this area near the fault, the most difficult mining challenge is over and tunnel advance rates are expected to improve significantly,” general manager Peter Whittal said.

“Getting through the crushed zone has been slow and difficult, with frequent stops for concrete reinforcing, but the good news was virtually no water and little gas has been encountered to date.”

Tunnelling started almost two years ago and should end towards the end of this month.

The mine is expected to produce 100,000t of saleable coal by the end of March 2009, a further 100,000t by the end of June 2009, and then an average of 1Mt per annum thereafter.

Pike River said the coal preparation plant was nearly complete, good progress had been made on the train loadout facility, and road and rail transport contracts were already in place.