China's Defence Minister Wei Fenghe said on Sunday that a war with the United States would be a disaster for the world. He said this while issuing a warning to Washington not to meddle in security disputes over Taiwan and the South China Sea.

China has been incensed by recent moves by US President Donald Trump's administration to increase support for self-ruled and democratic Taiwan, including US Navy sailings through the Taiwan Strait that separates the island from mainland China.

Wei, the first Chinese defence minister to speak at the Shangri-La Dialogue since 2011, said Beijing's military operations in Asia were purely aimed at self-defence, but it would not hesitate to counter an attack on its interests.

"China will not attack unless we are attacked," Wei said, cautioning that there would be dire consequences to any clash between China and the United States.

"The two sides realise that conflict, or a war between them, would bring disaster to both countries and the world."

The United States, like most countries, has no formal ties with Taiwan, but is its strongest backer and main source of weapons.

On Saturday, acting US Defence Secretary Patrick Shanahan told the Shangri-La meeting that the United States would no longer "tiptoe" around Chinese behaviour in Asia.

While Shanahan's speech was critical of China, his tone was often conciliatory. Wei took a more combative approach.

"No attempts to split China will succeed. Any interference in the Taiwan question is doomed to failure," said Wei, dressed in his uniform of a general in the People's Liberation Army.

"If anyone dares to split Taiwan from China, the Chinese military has no choice but to fight at all costs ... The US is indivisible, and so is China. China must be, and will be, reunified."