The Chinese military is mounting a show of force ahead of US House Speaker Nancy Pelosi's Asian tour, which could include a visit to Taiwan.

As China hardened its posture, despite growing concern that a miscalculation could increase the risk of conflict, it said it was holding live-fire drills in the Taiwan Strait and released footage of a similar exercise in the South China Sea.

The maritime administration in Fujian province said the exercise off the waters of Pingtan would be carried out between 8am and 9pm, adding that all vessels were banned from entering the area.

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Pingtan is about 125km (75 miles) from Taiwan's coast and about 185km from Taipei, its capital.

The exercise was announced on Thursday afternoon - hours before a phone conversation between Presidents Xi Jinping and Joe Biden aimed at reducing tensions - but not widely reported by Chinese media until Friday night.

During the call, their fifth since Biden took the office, Xi told Biden that the US should avoid "playing with fire" over Taiwan.

On Saturday, state broadcaster CCTV released a rare video footage of live-fire training by the Type 055 guided-missile destroyer Yanan in the South China Sea.

Li Jinwei, its captain, told CCTV that the training "focused on the practical application of new equipment to effectively enhance collaborative command and ... accelerate the formation of a new combat capacity".

Pelosi and her team have not confirmed that she will visit Taiwan, but if she goes ahead, this will be the first visit by a sitting US House speaker since Republican Newt Ginrich met president Lee Teng-hui 25 years ago.

Nancy Pelosi would be the most senior US politician to visit Taiwan since 1997. Photo: Bloomberg alt=Nancy Pelosi would be the most senior US politician to visit Taiwan since 1997. Photo: Bloomberg>

China considers Taiwan a breakaway province that must be brought under its control - by force if necessary. Any visit by a foreign government official to Taiwan is seen by Beijing as a breach of its sovereignty.

Both China and the US have been building up their military strength around the Taiwan Strait over the past weeks after reports emerged that Pelosi may visit the island along with Japan, South Korea and Singapore.

This week, the US 7th Fleet said it was deploying the USS Ronald Reagan from a port call in Singapore toward the South China Sea, a move the Pentagon said was part of a scheduled operation.