- AG600 was scheduled to make its first flight earlier this year
- It is unclear why the maiden flight was delayed
- The ground tests for the Chinese aircraft took place in April
China has stepped up research on advanced military equipment as it adopts a more muscular approach to territorial disputes in places such as the disputed South China Sea, rattling nerves in the Asia-Pacific region and the United States.
State television showed live images of the AG600 lifting off from Zhuhai airport in the southern province of Guangdong, which sits on the South China Sea coast.
Xinhua news agency said the aircraft was the "protector spirit of the sea, islands and reefs".
It had previously been scheduled to make its first flight earlier this year but it is unclear why it was delayed after ground tests took place in April.
State-owned Aviation Industry Corp of China (AVIC) has spent almost eight years developing the aircraft, which is roughly the size of a Boeing Co 737 and is designed to carry out marine rescues and battle forest fires.
The AG600's chief designer, Huang Lingcai, was quoted in the official China Daily earlier this month as saying it can make round trips without refuelling from the southern island province of Hainan to James Shoal, claimed by China but which is located close to Sarawak in Malaysian Borneo.
The aircraft has received 17 orders so far from Chinese government departments and Chinese companies. It has a maximum flight range of 4,500 km (2,800 miles) and a maximum take-off weight of 53.5 tonnes.
It can use conventional airports and also land and take-off from the sea.
China is in the midst of a massive military modernisation programme, ranging from testing anti-satellite missiles to building stealth fighters and the country's first indigenous aircraft carrier, to add to an existing one bought from Ukraine.
(This story has not been edited by NDTV staff and is auto-generated from a syndicated feed.)