In March, the Country Fire Authority sent an invoice to Hazelwood owners GDF Suez to recover costs from the enormous operation to put out the mine fire, which saw thousands of firefighters deployed into the mine pit to battle the blaze over many weeks.

But it is understood the company last week told the CFA in negotiations that it believed it should not have to pay the $18 million invoice.

That decision was confirmed in a statement released by the company to Fairfax Media on Monday, in which a spokesman said it was GDF Suez's position that it had already paid for the CFA's services through state fire service levy contributions over many years.

A CFA spokesman also confirmed it was seeking costs relating to the 2014 Hazelwood mine fire, but would only add that the Authority was in discussions with the mine owners "over its payment."

GDF Suez move to reject the bill now sets up a potential legal stoush between it and the state government. A government source told Fairfax Media the CFA's legal team had met recently with GDF Suez's lawyers to discuss the stand-off.

The fire at the Hazelwood brown coal mine was sparked on February 9 last year by spotting from a nearby, likely deliberately-lit bushfire. It lasted 45 days.

The fallout was significant. Beyond the enormous firefighting operation, state health authorities were forced to advise vulnerable residents of Morwell to leave their homes while the fire raged because of the health risks from the smoke.

The former Napthine government later commissioned an independent review of the disaster, which found shortcomings in GDF Suez's fire preparedness and the company's initial response to the outbreak.

The Andrews government has since reopened the inquiry to look at, among other things, whether the mine fire contributed to an increase in deaths in the Latrobe Valley, as feared by some residents.

State energy minister Lily D'Ambrosio told Fairfax Media she expected GDF Suez to be a good corporate citizen and reconsidered its opposition to the invoice.

Emergency Service Minister Jane Garrett also said: "More than 7000 firefighters worked tirelessly for 45 days under extremely challenging conditions to battle the mine fire."

"This invoice is a fair and reasonable price to pay for the massive emergency response effort which went into the Hazelwood mine fire," she said.

But GDF Suez's spokesman said the company had been "surprised and very concerned" to have received the invoice early this year.

"We believe the fire services levy – which is in effect an insurance policy – is designed specifically to cover fire suppression activities, whether they be large or small," he said.

The spokesman also pointed to millions of dollars already spent by GDF Suez related to the firefighting effort. In recent financial reporting the company said the fire and its response had cost it $40 million so far.

"We therefore don't believe it is fair, reasonable or within the scope of applicable regulations for the CFA to seek further payment from [GDF Suez]."

Local Latrobe Valley representatives hit out at the company's position. Voices of the Valley president Wendy Farmer said GDF Suez should take responsibility for the fire costs.

"They didn't prevent it getting into their mine. They didn't have the procedures and protocols in place," she said.

"[GDF Suez] should take responsibility. Why is the government topping-up an international company?"