Mainland airlines are increasingly flouting the official monopoly on jet fuel imports by loading as much fuel as they can at foreign airports and repatriating it for later use. They are doing this to get around the prohibitively high cost of fuel at home. According to industry estimates, as much as 30 per cent of the mainland's demand for jet fuel is being satisfied by such grey market imports. Essentially, mainland aircraft returning from overseas destinations will fill up their tanks with more fuel than needed for the journey, hoping for large savings on overall fuel costs. China Eastern Airlines company secretary Luo Zhuping acknowledged the practice. 'We will do it wherever we can and save money wherever we can.' He had no accurate statistics on the amount of fuel acquired this way, but said that it could account for about 30 per cent of China Eastern's overall needs. 'The oil we get overseas accounts for about 30 per cent of the fuel we use. International flights, including those to Hong Kong, account for about 50 per cent of our total revenue. 'Generally speaking, we fill up the aircraft overseas, but it depends on different circumstances and we balance economics with safety. We always take safety issues into account, such as the weight and number of passengers and the balance of the aircraft.' The phenomenon is probably limited to mainland carriers with a large exposure to international routes - namely Air China, China Eastern and China Southern Airlines. The fuel is also unlikely to be resold to other airlines, which would be illegal. The mainland jet fuel monopoly means that prices within China are as much as 40 per cent to 50 per cent higher than elsewhere in Asia.