Washington protests intercept by Chinese jets; China blames US

China denied US accusations that its jets conducted an unprofessional intercept of an American radiation sniffing surveillance plane in the East China Sea and urged Washington to stop such activities.

The two Chinese SU30 jets on Wednesday approached a WC- 135 Constant Phoenix aircraft a modified Boeing C-135 conducting a routine mission in international airspace in accordance with international law, Pacific Air Forces spokeswoman Lt Col Lori Hodge said in a statement.

The WC-135 crew characterised the intercept as unprofessional "due to the manoeuvres by the Chinese pilot, as well as the speeds and proximity of both aircraft," Hodge said.

She declined to provide further details and said the issue would be addressed with China through "appropriate diplomatic and military channels."

"We would rather discuss it privately with China," Hodge said in an email to The Associated Press.

"This will allow us to continue building confidence with our Chinese counterparts on expected manoeuvring to avoid mishaps."

In China, Defence Ministry spokesman Wu Qian said the American plane was conducting surveillance over the Yellow Sea the northern part of the East China Sea and that the Chinese jets moved to identify and verify the plane "in accordance with laws and regulations."