Japan on Thursday conveyed 'serious concerns' after Chinese fighter aircraft approached dangerously close to a Japanese military surveillance aircraft in the Pacific during the previous weekend.This occurrence followed the observation of two Chinese aircraft carriers navigating together in the Pacific for the first time, including within Japan's economic waters.Japan indicated this week that the aircraft carriers' activities - which China described as "routine training" - demonstrated the widening geographical reach of China's military operations.A spokesperson from Japan's defence ministry informed AFP on Thursday that Chinese fighter aircraft had flown "unusually close" to the Japanese patrol aircraft.On Saturday, a Chinese J-15 fighter from the Shandong aircraft carrier tracked a Japanese P-3C patrol aircraft for 40 minutes, followed by two J-15 jets doing the same for 80 minutes on Sunday, according to the spokesperson."Throughout these extended periods, the jets maintained an unusually close proximity to the P-3C, flying within 45 metres" of the patrol aircraft at identical altitude on both occasions, he stated.

On Sunday, the Chinese jets traversed the airspace approximately 900 metres ahead of the Japanese patrol aircraft - a distance coverable by a P-3C within seconds at cruising speed, the spokesperson added."These irregular approaches risk accidental collisions, hence we have expressed serious concerns" to China and requested prevention of similar incidents, stated a defence ministry release.The statement confirmed no Japanese military personnel sustained injuries.A second defence ministry spokesperson informed AFP that Japan's message was conveyed through diplomatic channels and between defence ministry officials of both countries.A comparable incident was previously reported over a decade ago in May and June 2014, when Chinese Su-27 fighter jets flew within 30 metres of Japan's military aircraft.Daisuke Kawai, who directs the University of Tokyo's economic security and policy innovation programme, told AFP earlier this week that the aircraft carrier movements' timing might correlate with US-China economic tensions. "Beijing calculated that the United States would be less willing or able to respond militarily at this precise moment, seeing it as an opportune time to demonstrate its expanding military capabilities," he said.