BG , the British gas and oil group, has signed a deal with China National Offshore Oil Corporation to sell liquefied natural gas from BG’s planned plant in Australia, opening up a new supply route to Asia.

CNOOC has agreed to buy 3.6m tonnes of LNG a year for 20 years and is taking small stakes in BG’s LNG plant and some of its gas fields. The supply represents about 5.3bn cubic metres of gas a year – about 8 per cent of China’s present demand.