Officials of Aviation Industry Corporation of China (AVIC) unveil the newly-made nose of amphibious aircraft AG600, during a ceremony at a factory in Chengdu, Sichuan province March 17, 2015. REUTERS/China Daily

SHANGHAI (Reuters) - The world’s largest amphibious aircraft, the China-made AG600, has passed engine tests and is expected to make its maiden flight in the first half of this year, state news agency Xinhua said.

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

State aircraft maker Aviation Industry Corporation of China (AVIC) has spent almost eight years developing the AG600, which is roughly the size of a Boeing 737 and is designed to carry out marine rescues and battle forest fires.

In November, AVIC displayed the plane at China’s biggest meeting of aircraft makers and buyers, after it completed production of the jet in July..

The aircraft has received 17 expressions of interest so far, Xinhua said late on Tuesday, but gave no further details. The aircraft has a maximum flight range of 4,500 km and a maximum take-off weight of 53.5 tonnes.

China also showed off its Chengdu J-20 stealth fighter in public for the first time at the November airshow and in June last year put into service a new, domestically-developed large transport aircraft.