ICBC Financial Leasing Co, China's biggest financial leasing company, is to start promoting sales of the domestically built C919 airliner - the narrow-body aircraft being produced by Commercial Aircraft Corporation of China Ltd.

The first prototype of the C919, to be used for test flights, was off the assembly line on Monday at COMAC's Shanghai factory.

ICBC Financial Leasing is so far the C919's biggest individual launching client, having placed 45 orders. But Cong Lin, its chairman, says it will be taking an active part in promoting the aircraft internationally, after the two sides signed a strategic agreement at the 2015 China Aviation Expo in Beijing in September.