Beijing's new airport saw four passenger planes completing test flights Monday morning.

Air China, China Eastern Airlines and China Southern Airlines respectively dispatched flagship models Boeing 747-8, Airbus 350-900 and A380. Meanwhile, Xiamen Airlines sent a Boeing 787-9 to take part in the test flights.

China will further open up to foreign investors and offer them treatment equal to that of domestic companies with firm protection of their legitimate rights, Premier Li Keqiang said at the Boao Forum for Asia.