Chinese military planes, mostly fighter jets, made more than 40 flights close to Tokyo-controlled islands at the centre of a territorial dispute on a single day this week, a press report said Saturday.

The flights took place on Tuesday, when eight Chinese marine surveillance ships entered the 12-nautical-mile territorial zone off the islands in the East China Sea, which Japan calls the Senkakus and China calls the Diaoyus, the Sankei Shimbun newspaper reported.

The conservative daily, citing senior government officials, said F-15 fighter planes from an airbase on the Japanese island of Okinawa scrambled to intercept the Chinese aircraft which flew in waves towards the skies over the islands.

"It was an unprecedented threat," one of the officials was quoted as saying.

Another said: "If such a show of force continues, it is feared it could lead to a situation where the (Japanese) air defence force may not be able to cope."

The report said the military planes included updated Sukhoi Su-27 and Su-30 fighter aircraft.

The report, which did not say whether the planes intruded into Japan's airspace, could not be immediately confirmed by Japan's Defence Ministry.

Chinese government ships have frequently sailed around the five Tokyo-controlled islands in recent months sparking diplomatic clashes.

But Tuesday's flotilla was the biggest to sail into the disputed waters in a single day since Tokyo nationalised part of the island chain in September.

On December 13, a Y-12 turbo-prop plane from China's State Oceanic Administration breached airspace over the disputed islands, prompting the launch of Japanese F-15s.

It was the first known incursion ever by a Chinese plane into Japanese airspace, the government said at the time.