Taiwan President Tsai Ing-wen called on Saturday for international support to defend the self-ruled island's democracy and way of life in the face of renewed threats from China.

The comments came a day after Chinese President Xi Jinping said the country's armed forces must strengthen their sense of urgency and do everything they can to prepare for battle.

"We hope that the international community takes it seriously and can voice support and help us," Tsai told reporters in Taipei, referring to threats by China to use force to bring Taiwan under its control.

If the international community did not support a democratic country that was under threat, "We might have to ask which country might be next?" Tsai added.

Taiwan is China's most sensitive issue and is claimed by Beijing as its sacred territory. Xi has stepped up pressure on the democratic island since Tsai from the pro-independence Democratic Progressive Party became president in 2016.

Xi said on Wednesday that China reserves the right to use force to bring Taiwan under its control but will strive to achieve peaceful "reunification" with the island.

In response, Tsai has said the island would not accept a "one country, two systems" political arrangement with China, while stressing all negotiations needed to be carried out on a government-to-government basis.

Xi's Taiwan speech came just days after US President Donald Trump signed the Asia Reassurance Initiative Act into law, reaffirming the US commitment to the island's security.

Tsai on Saturday also urged China to have a "correct understanding" of what Taiwanese think and said actions such as political bullying were unhelpful in cross-strait relations.

China still 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.

Military urgency

China is eager to beef up its armed forces amid territorial disputes in the South China Sea and escalating tension with the United States over issues ranging from trade to the status of Taiwan.

The official Xinhua news agency said on Saturday Xi told a meeting of the top military brass that China faced increasing risks and challenges, and the armed forces must work to secure its security and development needs.

Xi, who is also chairman of the Central Military Commission, said the armed forces must devise strategies for the new era and take on responsibilities for preparing and waging war.

"The world is facing a period of major changes never seen in a century, and China is still in an important period of strategic opportunity for development," he was quoted as saying.

He said the armed forces needed to be able to respond quickly to emergencies, needed to upgrade their joint operations capabilities, and nurture new types of combat forces.