Opponents of the controversial Shenhua Watermark coal project in northern NSW have launched an advertising blitz against the mine.
Former independent MP for New England Tony Windsor appears in the television ads along with Liverpool Plains farmers.
"They are mega mines over the top of the biggest water system in the Murray Darling so the risks in terms of those groundwater systems could be catastrophic," Mr Windsor tells viewers.
But Agriculture Minister Barnaby Joyce, who is also against the mine, took aim at Mr Windsor who sold his farmland property to a subsidiary of Whitehaven Coal in 2010.
"I think it's just a little bit convenient when 30 kilometres away from one mine is another mine which Mr Windsor made himself a multi-millionaire out of," he told ABC radio.
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Mr Joyce refused to say whether he had asked Prime Minister Malcolm Turnbull to overturn the government's approval of the Shenhua project.
"Any discussions I've had with Mr Turnbull I'll keep private," he said.
