China has developed the world's first portable sonic gun for riot control, the Chinese Academy of Sciences said.

The rifle-shaped instrument, which was jointly developed with military and law enforcement, is designed to disperse crowds using focused waves of low frequency sound, the academy's Technical Institute of Physics and Chemistry website said on Wednesday.

The device's "biological effect" would cause extreme discomfort, with vibrations in the eardrums, eyeballs, stomach, liver, and brain, scientists said.

Studies dating to the 1940s found that low frequency sound energy could, depending upon intensity and exposure, cause dizziness, headaches, vomiting, bowel spasms, involuntary defecation, organ damage and heart attacks.