China has conducted the first test-flight of its J-20 stealth fighter, Chinese President Hu Jintao has confirmed to US Defence Secretary Robert Gates.
The confirmation came after images of the 15-minute flight in Chengdu appeared on several Chinese websites.
Mr Hu said that the flight had not been timed to coincide with Mr Gates' visit, the US defence secretary said.
The US is currently the only nation with a fully operational stealth plane.
But both Russia and China are known to be working on prototypes of stealth fighters, which are invisible to radar.
Mr Gates' three-day visit to Beijing comes amid US concern over the speed at which China's military is modernising and upgrading its technology.
"I asked President Hu about it directly, and he said that the test had absolutely nothing to do with my visit and had been a pre-planned test. And that's where we left it," Mr Gates was quoted as saying by Reuters news agency. 'Take some time'
Leaked images of what was said to be China's J-20 fighter first appeared earlier this month during taxi tests at the Chengdu Aircraft Design Institute.
On Tuesday, the plane took off and flew for about 15 minutes, according to eyewitness accounts published on unofficial Chinese web portals.
A video clip of the flight was also posted on the web.
China says it expects the stealth plane to be operational some time between 2017 and 2019.
But earlier this month the Pentagon played down concerns over the fighter.
"Developing a stealth capability with a prototype and then integrating that into a combat environment is going to take some time," said US director of naval intelligence Vice Admiral David Dorsett.
China's official military budget quadrupled between 1999 and 2009 as the country's economy grew. In 2010 it stood at $78bn (£50bn).
But the US has by far the largest defence budget in the world at just over $700bn.
