The claims of a successful second test flight for the advanced fighter follow China's warning in late March that it faced an increasingly volatile Asian region where the United States has expanded its strategic footprint.
Some analysts have said that the first few photos of the J-20 suggest that China may be making faster-than-expected progress in developing a rival to Lockheed Martin's F-22 Raptor, the world's only operational stealth fighter designed to evade detection by radar.
The latest pictures may heighten concern about China's military build-up, including possible deployment in 2011 of its first aircraft carrier and a new anti-ship ballistic missile that is seen as a threat to U.S. aircraft carriers.
Chinese military and political sources say Beijing could launch its first aircraft carrier in 2011, a year earlier than U.S. military analysts had expected.