General Li Zuocheng, a member of the Central Military Commission, made the remarks during a meeting in Beijing with Admiral John Richardson, the chief of US naval operations.

China sees Taiwan as part of its territory to be reunified, despite the two sides being ruled separately since they split in 1949 after a civil war won by Mao Zedong's communists.

The self-ruled island has its own currency, flag and government, but is not recognised as an independent state by the UN.

Beijing has said it will not hesitate to use force if Taipei formally declares independence, or in the case of external intervention -- including by the United States, the island's most powerful unofficial ally.

"The Taiwan issue is an internal matter of China, concerns China's fundamental interests and the national feelings of the Chinese people, and no outside interference will be tolerated," Li Zuocheng said in a statement released by the Ministry of Defence.

"If anyone wants to separate Taiwan from China, the Chinese army will defend the unity of the motherland at any cost," he told the the US Navy chief.

In recent months, US Navy ships have repeatedly passed through the Taiwan Strait, which separates mainland China from the island.

Beijing views any ships passing through the straits as essentially a breach of its sovereignty -- while the US and many other nations view the route as international waters open to all.

A recent US law encouraging mutual visits between US and Taiwanese officials has also angered Beijing.

Washington, which broke diplomatic relations with Taipei in 1979 to recognise Beijing remains the island's most powerful ally, and its main arms supplier.