Mr Tinkler, the former owner of Patinack Farm, appeared at a planning assessment commission in Muswellbrook on Wednesday to speak "on behalf of the Drayton workers", who he said had been treated as "collateral" in the mine's approval process.

Declaring himself as "a bankrupt" with "no economic interest" in Drayton South, Mr Tinkler said he was "here purely out of my own interest".

"Perhaps if the mine is approved I may be fortunate enough to get a job," he said.

The existing Drayton mine - which closed last month - is owned by Anglo American. Located only a kilometre from two major horse studs, it has become the flash-point of an increasingly bitter fight between the two industries.

However Anglo doesn't intend to operate the expanded mine if it is approved, and a company that Mr Tinkler has links to - Australian Pacific Coal - has been speculated as a potential buyer of the mine.

Outside the meeting Mr Tinkler said he was "not involved" in Australian Pacific Coal, but when pushed admitted his family "has a holding".

"But that's something for Australia Pacific Coal, I'm not involved," he said.

Mr Tinkler used his speech to lash out at his former colleagues in the breeding industry, saying arguments of "reputational harm" caused by the mine were "preposterous".

Mr Tinkler said horse breeding was a "merry-go-round of scandal", noting leading trainer Chris Waller's horse testing positive for the drug ice last week, and reports Racing NSW is investigating claims another trainer, Gerald Ryan, over claims he sexually assaulted a jockey 20 years ago.

"The horse industry is one I know well, having invested in it heavily previously," he said.

"To claim mining would do reputational harm I think is preposterous.

"I could go into a lot more detail about what I know about the underbelly of the horse breeding industry but I think there's plenty of books out there.

"There might even be another one shortly."

Mr Tinkler - also the former owner of the Newcastle Knights and Jets sporting franchises - staunchly defended the industry in which he made his fortune, saying Drayton South was "a very economic project and one that will support over 500 families".

"The Hunter Valley is an industrial area in the fabric of its existence," he said.

"It's a sad state of affairs that these two important regional employers have to clash over this, but make no mistake this is being driven by the horse industry.

"The mining industry is not looking to pick a fight here. Anglo America has modified it's consent to the point where the footprint and visual impact are removed from the horse studs.

"I would hate to see Coolmore and Godolphin leave the Hunter Valley but that is their choice.

"The Hunter Valley and the horse industry will continue if they choose to go. The Hunter Valley needs Drayton South."

The commission is due to hear from 50 speakers on Wednesday, and will resume again on Thursday.

The large crowd at the meeting was filled with spectators wearing either Coolmore or Godolphin uniforms.

While Anglo American insists it has proven that that the mine expansion will have no impact on the breeding farms, Dr Cameron Collins, the president of the Hunter Thoroughbred Breeders Association, disagreed.

"I think there are various versions of coexistence," he said.

"Coexistence can't work without boundaries.

"Traditionally the open-cut coal mining industry has been well separated from the thoroughbred breeding industry, and it's only this proposal where there's a potential for a mine to be less than a kilometre from two of the biggest horse studs in Australia.

"We think that's unacceptable."

Among the listed speakers on Wednesday are Tom Magnier from Coolmore Stud, and Anthony Cummings, the trainer and son of Bart Cummings.

The Newcastle Herald