Taiwan said Tuesday that soldiers on one of its tiny frontline islands just off China's mainland were on heightened alert following what it called provocations by Chinese civilian drones.

Beijing claims democratic Taiwan as its own territory and has never renounced the use of force to bring the self-ruled island under its control.

In addition to military pressure from Chinese warplanes and vessels that maintain a near-daily presence around the island, Taiwan has faced incursions from civilian and unidentified drones that surveil and harass its troops.

Taiwan's military said in a statement that soldiers stationed on Erdan island had been required to "increase their vigilance in surveillance" in response to "Chinese netizens frequently using drones to provoke".

Erdan, which lies five kilometres (three miles) from the Chinese coast, is part of Taiwan's frontline Kinmen Island chain.

The Kinmen Defence Command also said in a statement that it will enhance the training of soldiers on the handling of drones, including taking "appropriate countermeasures depending on the level of threat".

The statement came after local media reported on a video posted to YouTube last week allegedly showing drone footage of soldiers and military facilities on Erdan.

The video was accompanied by a caption reading "Taiwanese soldiers on Erdan island are scared away by a Chinese drone." 

In 2022, Taiwanese soldiers on Kinmen shot down an unidentified civilian drone following a visit to Taipei by then-US House speaker Nancy Pelosi.

The drone and other incursions follow a pattern of what experts dub "grey zone" actions -- tactics that fall short of outright acts of war -- which have ramped up since the 2016 election of President Tsai Ing-wen.

Political tensions have also risen since January after Tsai's deputy Lai Ching-te -- whom Beijing considers a "separatist" -- was elected as president, and amid an ongoing row between China and Taiwan over a fatal boat incident.