"After a busy period working with partners and allies in the East China Sea, we are now en route through the Taiwan Strait to visit Vietnam and the Vietnam People's Navy," read a tweet from the official account for HMS Richmond, a frigate deployed with Britain's aircraft carrier strike group.

Local media said it was the first time a British warship had transited through the narrow waterway separating Taiwan and mainland China.

The British navy survey ship HMS Enterprise transited through the strait in 2019. The UK's defence ministry did not respond to a request for comment.

US warships regularly conduct "freedom of navigation" exercises in the strait and trigger angry responses from Beijing, which claims Taiwan and surrounding waters -- and almost all of the South China Sea.

The US and most other countries view those areas as international waters that should be open to all vessels.

China's initial response to the British warship's passage was muted on Monday.

"We hope the relevant countries can do more to build mutual trust between countries and uphold peace and security in the region," foreign ministry spokeswoman Hua Chunying told reporters.

Until recently, Washington was the main global power willing to sail through the Taiwan Strait.

But a growing number of US allies have transited the route as Beijing intensifies its military threats towards Taiwan and solidifies its control over the disputed South China Sea.

Canadian, French and Australian warships have all made voyages through the Taiwan Strait in recent years, sparking protests from China.

Taiwan's defence minister Chiu Kuo-cheng confirmed to reporters that a foreign vessel had sailed through the waterway but did not state which country it was from.

Taiwan's 23 million people live under constant threat of invasion by authoritarian China, which has vowed to seize the island one day -- by force if necessary.

Beijing has stepped up military, diplomatic and economic pressure on Taiwan since the election of President Tsai Ing-wen in 2016, who views the island as "already independent".

Last year, Chinese military jets made a record 380 incursions into Taiwan's defence zone, and the number of incursions for the first eight months of this year has already exceeded 400.