A Chinese magazine may have accidentally committed espionage after it published what appeared to be the first image of a top-secret missile system.

The apparent gaffe came in a centrefold graphic devoted to China's new H-6N strategic bomber in the latest edition of Modern Ships, a government-produced magazine.

The H-6N, which is modelled on the Soviet Union's now retired Tu-16 Badger bomber, is a long-range aircraft designed to project Chinese air power into the western Pacific.

But in the image published in Modern Ships showed the aircraft with a never-before-seen ballistic missile strapped beneath its fuselage.

The huge missile is unlike any known Chinese weapons system and analysts believe it may be the first glimpse of an air-launched ballistic missile (ALBM) Beijing is known to have been working on.