Asked whether he would support a levy on shoppers, he said: "I'll make sure we have a yarn to the retailers first before we suggest anything first". Credit:Andrew Meares "The Clarence-Morton basin has very good petroleum potential," investors were told of a 16,000 square kilometre region in the state's northern rivers. "Almost all wells drilled … have yielded gas and/or oil". Those words were published just months after several NSW Nationals MPs declared the state's north "CSG free" after the state government spent $25 million buying out mining companies with the right to explore the region. The buy-back followed a bruising 2015 NSW election for the National party, where a CSG-backlash cost the party a seat to the Greens and 20-points swings in the north. Senior Nationals warned voters would desert the party "for a generation" if they did not stop mining. (The party stopped short of endorsing a full ban but MPs said a buy-back of licences had the same effect).

The area of CSG potential. The impact on federal politics remains to be seen. But the basin extends over two key marginal seats: Page (2.5 per cent) and Labor-held Richmond (3 per cent). New England has not been singled out for uranium exploration before. The Greens were the main beneficiary of the 2015 state backlash and are this year trying to leapfrog the Nationals to claim Richmond from Labor.

"This is a huge concern for our region," said federal Greens candidate for Richmond, Dawn Walker. "How can we trust the Nationals when their government is busy spruiking the potential of the region as a coal seam gas field to overseas investors?" But a Nationals source said the party had received an absolute guarantee from its coalition partners in NSW that no further mining would take place in the north and that would not be broken. The document also raises the possibility that the state government is seeking to generate international interest in exploring new parts of NSW for uranium, which has potential implications for a third tight federal election contest. Under the headline "Uranium in NSW: A Greenfields Opportunity" investors were told NSW represented an opportunity for stable investment in a state with "known uranium potential". Investors were presented with maps highlighting potential uranium deposits in Broken Hill and Lachlan in the state's central west, but also the New England region.

It is not known if those deposits extend to the federal electorate named New England, where Deputy Prime Minister Barnaby Joyce is defending his seat by distancing himself from state government mining policies including its planning approval of the Watermark coal mine on the Liverpool Plains. The state government moved to allow uranium exploration in 2012, but only "low-impact exploration" to help identify potential reserves and not mining. That did little to excite the market. Only one company accepted a state government invitation to apply for an exploration licence and soon dropped out. The NSW division of energy and resources issued an apology for the material on Wednesday, saying it was made in error and would now be withdrawn. The government department said it should have made clear that it is government policy to prohibit coal seam gas exploration in the state's northern rivers.

"[The division also] acknowledges and accepts that our materials may have given the impression that exploring for uranium in NSW is a current opportunity for investors," the department said. "We acknowledge that this is not in line with the government's resources agenda." The state government did not say if the conference brochures were an attempt to generate international interest in uranium exploration. "The Trade & Investment material notes the potential for certain resources to exist in NSW," a spokesman for the state's energy minister, Anthony Roberts, said. "However … the NSW government has no intention of any further petroleum or gas exploration in the Northern Rivers." The state government said it was changing the way exploration licences were issued to ensure social and environmental impacts were assessed before decisions were taken. The document also says that the "CSG potential" of large parts of the NSW Riverina region, from Griffith to Mildura, is "currently being evaluated".