It is the first time Taiwanese forces have downed a drone and comes at a time when tensions between Beijing and Taipei are at their highest in decades.

Taiwan's defence ministry said a small civilian drone entered a "restricted zone" above Shiyu Islet, a small rock that lies between the Chinese mainland and Taiwan's Kinmen islands.

"The stationed troops followed procedures to warn off the drone but to no avail. The drone was shot down in defensive fire," the defence ministry said.

Kinmen lies just a few miles off China's coastline and Taiwan has reported a spate of incidents in the last two weeks where small drones have hovered over soldier outposts.

Videos have been circulated on both Taiwanese and Chinese social media, with one showing Taiwanese soldiers hurling rocks at a drone to drive it off.

Taiwan's military and President Tsai Ing-wen warned this week that they might resort to live fire if the drones ignore warnings to leave.

On Monday, Chinese foreign ministry spokesman Zhao Lijian said the incursions were not "anything worth making a fuss about" as the drones were "flying around Chinese territory".

Taiwan lives under constant threat of invasion by China, which claims the self-ruled democratic island as part of its territory to be seized one day -- by force if necessary.

The drone incursions over Kinmen increased as Beijing embarked on a show of force in retaliation for US House Speaker Nancy Pelosi's visit to Taiwan last month.

For a week after Pelosi's visit, China sent warships, missiles and fighter jets into the waters and skies around Taiwan, its largest and most aggressive exercises since the mid-1990s.

It is not clear who is flying the drones.

Given Kinmen lies so close to the Chinese mainland, a civilian could feasibly fly a commercial drone that distance.

However, China has also stepped up so-called "greyzone" tactics against Taiwan in recent years to pressure the island.

"Greyzone" is a term used by military analysts to describe aggressive actions by a state that stop short of open warfare and can use civilians.

Civilian Chinese fishing and sand dredging vessels, for example, have increasingly entered waters around Taiwanese outlying islands, including Kinmen.

China has also ramped up incursions by warplanes into Taiwan's air defence identification zone as a way to test defences and wear out the island's own fleet of ageing fighter jets.