Australia has admitted a huge new energy project to supply Asian markets could raise national greenhouse gas emissions by up to one percent if ambitious efforts to capture them fail. Environment Minister Peter Garrett made the comments just hours after approving the Gorgon field, which will provide China and India with tens of billions of dollars of liquefied natural gas. He said plans to pump carbon dioxide emissions into sandstone rock at Barrow Island, at the site of the project off Western Australia, were untested on such a scale. 'It certainly is a greenhouse-gas intensive project,' Garrett told public broadcaster ABC late on Wednesday. He added that total emissions, if they leaked, could approach one percent of the national total. 'It may be up to that figure. I don't have the figures to hand,' he said. The Gorgon field, thought to hold more than 40 trillion cubic feet of gas, is expected to create thousands of jobs and pump billions of dollars into Australia's economy. Last week ExxonMobil, a joint venture partner with Chevron and Shell, signed a 41 billion US dollar contract with PetroChina in Australia's biggest ever trade deal. ExxonMobil also has a 21 billion US dollar contract with India's Petronet. Garrett approved the development, as widely expected, on Wednesday subject to 28 environmental conditions. He said the carbon capture plan needed to be done 'carefully and prudently.' 'The fact is that CO2 will be injected basically into sandstone,' said the former Midnight Oil frontman. 'There are faults in the substrata there, but faults can operate in different ways. They can operate as an effective capture mechanism or they can operate as a leakage mechanism.' Australia has pledged to cut the release of greenhouse gases blamed for global warming by between five and 25 percent by 2020, although an emissions trading scheme was defeated in the Senate this month. 