Speaking at the Sydney Mining Club yesterday, Hannigan said every effort was being made to keep discipline on costs for the project but it was inevitable that there be some variation to figures quoted in the company’s prospectus when it floated last year.

"Particularly when you've got a very tight market, there are risks there," he said. "I don't expect us to blow it out like other companies, where costs are double what they thought they were."

Aston would attempt in the next six months to secure 40% of the cost of building its $212 million coal processing plant to help fix costs, Hannigan said.

It would, however, have to pay up to $30 million more than the stated prospectus figure of $20 million for acquiring property around the mine in the Gunnedah Basin.

Aston had secured state government approvals two weeks ago, before the NSW election date later this month when it was expected that a new Coalition government would introduce a “transitional” period when approvals would cease and greater consultation with agricultural landholders would begin.

The company is still expecting construction to begin in the fourth quarter 2011 and first commercial coal to be produced by 2012. The mine will produce a mix of thermal, semi-soft coking and pulverised coal injection coal, with projected sales expected to reach 10 million tonnes per annum by 2014.

Although Aston still needed to secure more port access at Newcastle, Hannigan said there would be enough port capacity for the company, even if it meant negotiating arrangements with existing producers.

Maules Creek would maintain its low strip ratio of 6.4:1 during the mine’s 20-year mine life, delivering it a “structural cost advantage”

The project’s high-yield, low-ash coal could provide Aston with margins of about $93 per tonne.

Maules Creek is the seventh-largest coal deposit and the fourth-largest metallurgical coal deposit in Australia, with capital costs at a fraction of those of greenfields projects in the Galilee Basin in Queensland, Hannigan said.

“It’s very rare for a mid-sized mining company to control an asset of this size and quality,” he said.