Thousands have taken to the streets of Taipei to express their anger at a new law in Beijing.
The protesters fear it could give their giant neighbour a legal basis for invasion. China has claimed sovereignty over self-ruled Taiwan since their split in 1949.
It has threatened to attack the island if it formally declares independence.
The new anti-secession law is topping the agenda at the opening of the annual session of China’s parliament where premier Wen Jiabao has underlined his commitment to pursue reunification.
Beijing says the legislation is designed merely to achieve this aim peacefully. Nevertheless, speaking today, China’s foreign minister struck a hawkish tone, voicing irritation at last month’s comments by Japan and the United States listing security in the Taiwan Strait as a common concern. Li Zhaoxing also sought to calm fears that the possible end of an EU arms embargo would lead to a shopping spree for weapons that Washington worries could be used in any conflict with Taiwan.
China has said it will boost its military budget by more than 12 percent this year.