The root causes of tensions across the Taiwan Strait lie with external forces and "Taiwan independence" agitators, both of which are exploiting each other, the Chinese defense minister said on Sunday, warning that the Chinese military will not hesitate for a second if anyone dares to separate Taiwan from China.

"Who is undermining stability across the Taiwan Strait? The answer is known to all," State Councilor and Defense Minister General Li Shangfu said at a plenary session of the Shangri-La Dialogue attended by delegations from about 40 countries.

They are Taiwan's Democratic Progressive Party which are soliciting foreign support for independence and some foreign forces which are attempting to contain China and interfere in its internal affairs, he said.

Li pointed out the DPP denies the 1992 Consensus and have continuously pushed for incremental "Taiwan independence", adding they have tried to erase the Chinese identity of Taiwan and manipulated public opinion.

Meanwhile, a big power has repeatedly sold arms to Taiwan, provided military training and upgraded official exchanges, the defense chief said, noting such moves greatly violate its own promises.

Just one day ago, United States Defense Secretary Lloyd Austin claimed in his speech at the Shangri-La Dialogue the US opposes unilateral changes to the status quo of the Taiwan Strait.

However, on the same day, the destroyer USS Chung-Hoon and the Royal Canadian Navy's HMCS Montreal passed through the Taiwan Strait, and were followed and monitored by the Chinese military in accordance with the law and regulations, according to a military spokesman.

Senior Colonel Shi Yi, spokesman for the People's Liberation Army's Eastern Theater Command, said the two countries were "deliberately stirring up trouble" in the Taiwan Strait, maliciously undermining regional peace and stability and sending wrong signals to "Taiwan independence" forces.

In his speech delivered at the security forum in Singapore, Li said the Taiwan question is the core of China's interests.

"It's an internal affair of China, which is the first indisputable fact," Li said.

"How to resolve the Taiwan question is a matter for us Chinese to decide. It brooks no interference from foreign forces."

The Cairo Declaration and the Potsdam Proclamation have made it clear Taiwan shall be restored to China as part of the post World War II international order, he said.

Any act to obscure or hollow out the one-China principle is "both absurd and dangerous", Li said. He added over 180 countries established diplomatic ties with China with the political commitment of abiding by the one-China principle, which has become a universally recognized basic norm governing international relations.

In addition, he sent a strong warning: "The more rampant the separatist activities for Taiwan independence are, the more resolute our countermeasures will be. All foreign interference is doomed to end in failure."

Li said China will strive for peaceful reunification with the utmost sincerity and greatest effort, but makes no promise to renounce the use of force.

"If anyone dares to separate Taiwan from China, the Chinese military will not hesitate for a second," he warned.