SYDNEY • A British warship will sail from Australia through the disputed South China Sea next month to assert freedom-of-navigation rights, a senior official has said, in a move likely to irk Beijing.

China claims nearly all of the resource-rich waterway and has been turning reefs and islets into islands and installing military facilities such as runways and equipment on them.

British Defence Secretary Gavin Williamson said HMS Sutherland, an anti-submarine frigate, will arrive in Australia later this week.

"She'll be sailing through the South China Sea (on the way home) and making it clear that our navy has a right to do that," he told The Australian newspaper yesterday after a two-day visit to Sydney and Canberra.

He would not say whether the frigate would sail within 12 nautical miles of a disputed territory or an artificial island built by the Chinese, as United States ships have done. But he said: "We absolutely support the US approach on this, we very much support what the US has been doing."

Last month, Beijing said it had dispatched a warship to drive away a US missile destroyer which had "violated" its sovereignty by sailing close to a shoal in the sea.

Mr Williamson said it was important that US allies such as Britain and Australia "assert our values" in the South China Sea, which is believed to hold vast oil and gas deposits and through which US$5 trillion (S$6.6 trillion) in trade passes annually.

"World dynamics are shifting so greatly. The US can concentrate on only so many things at once," he said. "The US is looking for other countries to do more. This is a great opportunity for the United Kingdom and Australia to do more, to exercise leadership."

When asked yesterday about a possible freedom-of-navigation voyage by the British, China's Foreign Ministry spokesman Geng Shuang said all countries have "navigation and overflight freedom in the South China Sea".

"We hope other countries will stop stirring up trouble," he said.

Chinese state media reported yesterday that China has started building the world's largest test site for unmanned ships - a technology with both civilian and military applications - off a port in the South China Sea, home to a number of disputed islands also claimed by South-east Asian countries.

The test area is being constructed off the southern port city of Zhuhai bordering Macau, Xinhua reported.

Unmanned or "autonomous" ship technology, still in its infancy, would allow both civilian and military craft to be remotely controlled.

Last December, China defended its construction on the disputed islands in the waters as "normal" after an American think-tank released new satellite images showing the deployment of radar and other equipment.

In a separate interview with broadcaster ABC, Mr Williamson warned of the need for vigilance against "any form of malign intent" from China, as it seeks to become a global superpower.

"Australia and Britain see China as a country of great opportunities, but we shouldn't be blind to the ambition that China has and we've got to defend our national security interests," he said.

AGENCE FRANCE-PRESSE