China has voiced firm opposition to the US Air Force for using its planes to disguise as civilian aircraft from other countries, and urged the US to stop such provocations.

"It's a common trick for the US Air Force to impersonate the transponder code of civilian aircraft from other countries. It's known that by disguising its planes, US reconnaissance planes have entered the South China Sea over 100 times, "a Chinese Foreign Ministry spokesperson said at a routine press briefing on Wednesday.

The Twitter account of the South China Sea Probing Initiative 

The spokesperson, Wang Wenbin, was responding to a recent incident in which a US Air Force aircraft electronically disguised itself as a Malaysian plane while flying over the South China Sea.

China firmly opposes the actions of the US that seriously violate international aviation regulations, severely disrupt the aviation order and safety of the relevant airspace, and threaten the security of China and countries in the region, Wang said. 

"We urge the US to immediately stop such dangerous provocations, avoid accidents from happening in the sea and air. China will continue to work with other countries in the region to firmly safeguard the freedom and security of navigation, and conduct patrols in the South China Sea, and maintain the peace and stability in the region,"he said.

Earlier last month, China's Defense Ministry accused the US military of "seriously interfering in normal activities" because of its surveillance activities over the no-fly zone in the northern military region.