Beijing has raged at a trip to Taiwan last week by US House Speaker Nancy Pelosi -- the highest-ranking elected American official to visit in decades -- staging days of air and sea drills around the island that raised tensions to their highest level in years.

Taiwan has accused China of using the Pelosi visit as an excuse to kickstart drills that would allow it to rehearse for an invasion.

Lou Woei-jye, spokesman for Taiwan's Eighth Army Corps, told AFP its forces fired howitzers and target flares as part of the defensive drill on Thursday morning.

The exercise in Taiwan's southernmost county of Pingtung began at 0830 am local time (0030 GMT) and lasted about an hour, he said.

Artillery tucked in from the coast was lined up side by side, with armed soldiers in units firing the howitzers out to sea one after the other, a livestream showed.

Taiwan held a similar drill on Tuesday in Pingtung. Both included the deployments of hundreds of troops, the military said.

The military has played down their significance, saying they were already scheduled and were not in response to China's war games.

"We have two goals for the drills, the first is to certify the proper condition of the artillery and their maintenance condition and the second is to confirm the results of last year," Lou said, referring to annual drills.

The latest exercise came after China's military indicated its own drills had come to an end Wednesday, saying its forces "successfully completed various tasks" in the Taiwan Strait while vowing to continue patrolling its waters.

But in the same announcement, China added that it would "continue to carry out military training and prepare for war".

In a separate white paper published Wednesday, China's Taiwan Affairs Office said Beijing would "not renounce the use of force" against its neighbour and reserved "the option of taking all necessary measures".

"We are ready to create vast space for peaceful reunification, but we will leave no room for separatist activities in any form," it said in the paper.

Taiwan routinely stages military drills simulating defence against a Chinese invasion, and last month practised repelling attacks from the sea in a "joint interception operation" as part of its largest annual exercises.

In response to the Chinese military revealing it was bringing drills to an end Wednesday, Taiwan's army said it would "adjust how we deploy our forces... without letting our guard down".