Taiwan’s defence ministry says it has detected eight Chinese fighter jets crossing the median line of the Taiwan Strait, as well as one Chinese balloon, in 24 hours.

Taiwan, which China claims as its territory, has repeatedly complained of Chinese military activity around the island in the past four years.

China has been stepping up its missions near Taiwan as the January 13 presidential and parliamentary elections on the island approach.

Taiwan’s defence ministry said on Sunday the Chinese J-10, J-11 and J-16 fighter jets had crossed the median line at points to the north and centre of the strait.

The median line once served as an unofficial barrier between the two sides but Chinese planes now regularly fly over it.

Taiwan sent its forces to monitor, the ministry said.

Spy in the sky

The ministry also reported another Chinese balloon in the strait, the latest in a spate of what Taiwan says is most likely for monitoring the weather, driven by prevailing winds at this time of year.

It said the balloon was spotted after crossing the median line late on Saturday morning 180km northwest of the northern Taiwanese port city of Keelung at an altitude of approximately 6100 metres.

The balloon headed east and disappeared about an hour later, the ministry said.

The potential for China to use balloons for spying became a global issue in February when the United States shot down a Chinese surveillance balloon after allowing it to traverse North America and linger over military installations.

China said the balloon was an innocent civilian craft that accidentally drifted astray.

-AAP