Chinese leader Xi Jinping said on Saturday reunification with Taiwan must happen and will happen peacefully, despite a ratcheting-up of China's threats to attack the island.

Xi spoke on at an official celebration in Beijing's Great Hall of the People the focused largely on the need for the ruling Communist Party to continue to lead China as the country rises in power and influence.

“Reunification of the nation must be realised, and will definitely be realised,” Xi told an audience of politicians, military personnel and others gathered in the hulking chamber that serves as the seat of China's ceremonial legislature. “Reunification through a peaceful manner is the most in line with the overall interest of the Chinese nation, including Taiwan compatriots.”

The celebration was in honour of the 110th anniversary of the Chinese revolution in 1911 leading to the overthrow of the Qing dynasty and establishment of the Republic of China led by Sun Yat-sen. October 10 is celebrated in Taiwan as National Day and Xi's address touched on common aspirations for a unified future, despite the stark differences between China's authoritarian one-party system and Taiwan's vibrant multi-party democracy.

Xi's remarks came just days after the Chinese military sent a record number of military aircraft flying towards Taiwan in exercises that the self-ruled island has called a threat. Over the course of four days, starting last week, the People's Liberation Army flew fighter jets, bombers and airborne early warning aircraft 149 times towards Taiwan, with the largest manoeuvre involving 52 jets at once.

Taiwan and China split in 1949 amid civil war, with the then ruling Nationalist Party fleeing to the island as Mao Zedong's Communists swept to power on the mainland.

Taiwan this year will feature a rare display of military equipment, including missiles and a performance by the Air Force with fighter jets in its National Day celebration to be held Sunday in front of the Presidential Office Building in the centre of the capital, Taipei.

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That marks the first inclusion of military hardware in the event in years, and the first since Tsai Ing-wen took office in 2016, as tensions with China have risen to unprecedented levels.

Local media coverage of rehearsals for the celebration showed large missile launch vehicles driving on Taipei's streets, although the missiles themselves were not directly visible.

In the past, the Taiwanese government has kept its missile capabilities out the public eye to avoid appearing provocative, said Kuo Yu-jen, a defence studies expert at the Institute for National Policy Research in Taiwan.

“But recently China’s attitude towards Taiwan has become overly assertive so .... they must demonstrate that Taiwan has the ability to deter China’s threat,” Kuo said.

In years past, the national day celebration has also featured choreographed performances by motorcycle riding military police, anti-terrorism demonstrations by special forces and overflights by the island’s air force. However missiles were not part of that display.

“I think this is to raise Taiwan’s people’s morale,” said Fan Shih-ping, a professor of political science at National Taiwan Normal University.

Tsai has placed a higher premium on national defence that her predecessor from the more China-friendly Nationalist Party, launching a revitalization of the island’s shipbuilding industry and commissioning a programme to build submarines domestically.

She has also instituted reforms in the military, including improving benefits for military personnel and even increasing the quality of food serves in the messes.

Taiwanese Defence Minister Chiu Kuo-cheng told legislators Wednesday that the situation with China “is the most severe in the 40 years since I’ve enlisted”. Chiu later told reporters that he believed China would have “comprehensive” capabilities to invade Taiwan by 2025.

Since the split, Taiwan has been self-ruled, but its sovereignty is denied by Beijing, which has refused to renounce the option of using force to bring the island under its control.

Beijing has also sought to isolate Taiwan internationally by barring it from the United Nations and other international organisations and opposing official contacts between its government and nations that recognise China, especially the United States, which is legally bound to consider threats against Taipei a matter of “grave concern”.

US and Japanese officials have also warned that China's growing capabilities pose a rising threat to Taiwan's security and that of the region.

“Taiwanese separatism is the biggest obstacle to the motherland's reunification,” Xi said in his address, adding that those who advocated for the island's formal independence would be “condemned by history”.

“The Taiwan question is purely China’s internal affair, which tolerates no external interference," Xi said. “No-one should underestimate the Chinese people’s strong determination, will and capability to safeguard national sovereignty and territorial integrity."