"China poses the biggest challenge of our age to global security and prosperity. They are increasingly authoritarian at home and assertive abroad," Sunak told reporters after the G7 summit in the Japanese city of Hiroshima.

Sunak said Britain and other G7 countries would pursue a common approach to reduce the challenges posed by China.

"This is all about de-risking - not de-coupling," he said. "With the G7, we are taking steps to prevent China from using economic coercion to interfere in the sovereign affairs of others," he added.

Last week Sunak's predecessor as prime minister, Liz Truss, became the best-known British politician to visit Taiwan since Margaret Thatcher in the 1990s, where she said the West should not "appease and accommodate" China.

Tensions have risen as China has become increasingly assertive about the self-governed island, which Beijing claims as its own. China has never renounced the use of force to bring Taiwan under its control.

Truss represents a more hawkish wing of Sunak's Conservative Party that opposes his approach to China, which involves seeking to engage in areas such as trade and climate change while trying to limit national security threats.

Sunak also said Britain would start training Ukrainian pilots this summer to support its air force in its war with Russia.

Joined by Volodymyr Zelenskiy, Sunak said no one wants peace more than the Ukrainian president but that peace conditions should be based on Ukraine's principles.

At the three-day summit the G7 signalled to Russia their readiness to stand by Ukraine for the long term.