China National Offshore Oil Corp (CNOOC) has signed its third long-term liquefied national gas (LNG) supply contract, Forbes reported, citing The South China Morning Post.   The report, citing sources, said the company signed a preliminary agreement several monts ago with Malaysia's Petronas for the long-term supply of gas for its LNG terminal in Shanghai, which is awaiting approval from Beijing. The Shanghai terminal has an annual capacity to regasify three million tonnes of LNG and is expected to come onstream in 2009, said Zheng Hongtao, a planning manager of the gas purchase department.