Global miner Rio Tinto looked set to abandon its $116 billion iron-ore joint venture with rival BHP Billiton , a deal unpopular with customers, regulators and many of Rio Tinto’s own investors.Rio Tinto shares firmed more than 2 percent after an Australian newspaper, quoting from an extraordinary leak of Rio Tinto boardroom discussions, said on Wednesday the world’s second-largest iron ore miner was determined to walk away from the venture.The Sydney Morning Herald quoted Rio Tinto Chairman Jan du Plessis addressing a board meeting on Monday in terms that assumed the joint venture was all but dead and buried."I think with regard to the and why it didn’t succeed -� we should simply work on the basis that both parties worked well and in good faith to make this thing work and both parties agreed, simultaneously, it wasn’t possible," du Plessis was quoted as saying in the front-page report. The venture was announced last year when Rio Tinto was heavily in debt and iron ore prices were less than half today’s prices. Under the deal, Rio Tinto would hand over 5 percent of its Australian iron ore operations to BHP Billiton for $5.8 billion, a price many Rio Tinto investors now view as too cheap.Rio Tinto said in a statement after the newspaper report that it had yet to make a final decision on the venture, though it confirmed the issue had been discussed at Monday’s board meeting."The board acknowledged recent communications from regulators that indicate potential obstacles to achieving clearance for the joint venture," it said.BHP Billiton said it remained committed to the proposed venture’s regulatory process but declined further comment.The venture also angered international steel mills, which feared the two miners would gain more power over pricing of the steel-making raw material, and also worried competition regulators in Asia and Europe."I don’t believe regulatory approval will be forthcoming," said UBS resources analyst Glyn Lawcock in Sydney."Steelmakers are up in arms," he added, noting that iron ore miners already made gross profit margins of around 80 percent.Rio Tinto and BHP Billiton shares both jumped more than 2 percent in Australian trade, in line with a stronger overall mining sector <.AXMJ>, up 2.2 percent.Rio Tinto is expected to announce in coming months long-term plans to expand its iron ore output by about 50 percent to 330 million tonnes a year, said analyst Charles Kernot at Evolution Securities in London."If they have a deal with BHP, some of that upside potential gets diluted, it doesn’t all accrue to Rio shareholders. The more work that the company does on it, perhaps the more value they’ll think they’re giving away, unless they can convince BHP to pay more for the equalisation payment," Kernot said.The two firms have been awaiting approval from competition regulators in Europe, Australia and Asia since last December.