China's domestically developed AG600, the world's largest amphibious aircraft, will make its maiden flight in late May from the southern city of Zhuhai, the official Xinhua news agency said on Thursday.

China has stepped up research on advanced military equipment as it adopts a more muscular approach to territorial disputes in places such as the busy South China Sea waterway, rattling nerves in the Asia-Pacific region and the United States.

The aircraft will take its first flight over land and then another on water in the second half of 2017, Xinhua said, citing its manufacturer, state-owned Aviation Industry Corp. of China (AVIC).

AVIC has spent almost eight years developing the aircraft, which is roughly the size of a Boeing 737 and is designed to carry out marine rescues and battle forest fires.

The aircraft has received 17 expressions of interest so far, Xinhua added. It has a maximum flight range of 4,500 km (2,800 miles) and a maximum take-off weight of 53.5 tonnes.