Japan condemned the incursion as a "serious violation" of its sovereignty, saying Beijing was becoming "increasingly active".

Japan, a close ally of Washington, said it had scrambled fighter jets after the two-minute incursion from 11:29 am (0229 GMT) on Monday by the Y-9 surveillance aircraft off the Danjo Islands in the East China Sea.

Asked about Tokyo's claims, foreign ministry spokesman Lin Jian said "the relevant Chinese departments are in the process of gathering information and verifying the situation".

"The two sides have maintained communication through existing working channels," he added.

"I would also like to emphasise here that China has no intention of intruding into the territorial airspace of any country," Lin said.