China will not rule out using force to bring Taiwan under its control, Xi Jinping has said.

Beijing reserves “the option to use all necessary measures” to extend its rule to the independent island republic it claims as part of “one China”, the president said in a speech devoted to the issue on Wednesday.

Tsai Ing-wen, Taiwan’s president, said Mr Xi should use peaceful means to resolve the mainland’s differences with Taiwan and respect its democratic values.

Mr Xi has made reunification a key policy issue and gave his address on the 40th anniversary of China’s decision to cease artillery bombardment of Taiwanese islands and open up communication.

Taiwan and China split in a civil war that brought the communists to power on the mainland in 1949. The rival nationalists set up another government on the island which lies about 100 miles off China’s coast.

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But the Chinese government has frequently sent military aircraft and warships to circle Taiwan in recent years, with Mr Xi piling pressure on the democratic island since Ms Tsai, from the pro-independence Democratic Progressive Party, became president in 2016.

In his speech at Beijing’s Great Hall of the People, Mr Xi said: “China must and will be united, which is an inevitable requirement for the historical rejuvenation of the Chinese nation in the new era.

“China won’t attack Chinese people. We are willing to use the greatest sincerity and expend the greatest hard work to strive for the prospect of peaceful reunification.

“After peaceful reunification, Taiwan will have lasting peace and the people will enjoy good and prosperous lives. With the great motherland’s support, Taiwan compatriots’ welfare will be even better, their development space will be even greater.”

But he added that “we do not promise to renounce the use of force and reserve the option to use all necessary measures” to achieve reunification and prevent Taiwanese independence.

The threat of force was aimed at Taiwan’s own independence forces as well as foreign powers who may seek to interfere, Mr Xi suggested, without elaborating in what was likely a reference to the US, Taiwan’s strongest supporter.

Mr Xi claimed that unification would be under a one-country, two-system framework that would respect the Taiwanese social system and way of life and guarantee their property rights, religious beliefs and other rights.

But similar past pledges over the future of Hong Kong have not prevented Beijing tightening its grip on the city, with activists voicing fears about growing pressure on democratic freedoms.