China's newest warplane, the J-20 stealth fighter, will make its first public flight at the Zhuhai Air Show, its manufacturer announced Monday, as Beijing flexes its long-range military muscles.

The J-20, "which military enthusiasts at home and abroad have watched closely", will make its first public flight demonstration, said Tan Ruisong, the president of China's state aerospace company AVIC.

China trailed the world in aerospace technology 20 years ago, he told a press conference, but was now at the leading edge.

Swift, stealthy, and armed with long-range missiles, the new J-20s represent a leap forward in China's ability to project power in Asia and compete in capabilities with the United States.

Beijing is seeking to modernise and upgrade its military both to protect its borders and project power into regions such as the South China Sea, a resource-rich waterway where it has disputes with several neighbours.

China's only international aerospace exhibition, held biennially in the southern city of Zhuhai, this year boasts its largest-ever display of military hardware and aircraft, with 11 exhibition halls, 430,000 square metres of indoor and outdoor viewing area, and 151 aircraft from 700 exhibitors from 42 countries and regions.

The show will also see the debut of the Y-20 transport aircraft, which can move heavy loads and carry out airlifts to assist military activities.

Chinese-made military assault vehicles, anti-aircraft missile systems, drones and fighter jets stood on display outside the exhibition centre.

AVIC chief Tan said his company had business in 80 countries and territories, with annual overseas sales exceeding 80 billion yuan ($11.8 billion).

The firm will firmly remember its "sacred mission" to serve China, he said. It would carry out the strategic plan of the Communist party, the government and the People's Liberation Army and "closely unite around the core leadership of comrade Xi Jinping".

AVIC, which earlier this year acquired British cabin interior supplier AIM Altitude, would "persistently struggle" to realise the dream of a great Chinese air force and a strong military, he added.

China is aggressively moving to develop its domestic weapons industry, from drones and anti-aircraft systems to homegrown jet engines.

In the past it has been accused of copying designs from Russian fighters, and some analysts say its next-generation J-31 stealth fighter bears a close resemblance to the US-developed F-35.

Another exhibitor, China South Industries Group Corporation, showed off 70 products focused on anti-terror operations, fast response forces and aircraft munitions.