Drawing parallels to modern China's founding father Sun Yat-sen, President Xi Jinping has pledged to oppose any attempts in Hong Kong or Taiwan to break away from the mainland, sending a warning to pro-independence advocates there.

In a 45-minute speech yesterday marking Sun's 150th birth anniversary, Mr Xi recounted the beliefs of modern China's first president that a unified country would benefit the people but one that is divided would face harm inevitably. And the latter is what China had experienced over the past century, added Mr Xi, alluding to the invasions by foreign countries like Japan and European powers. "It is our solemn pledge to the people and to history never to let the country be torn apart again. All forms of separatist activities will be resolutely opposed by the entire Chinese people," he added. "We will never allow any one, any organisation, any political party to remove a part of territory from China in any form and at any time."

But Mr Xi - speaking at a memorial at Beijing's Great Hall of the People ahead of Sun's birthday today, which was attended by the Chinese Communist Party's (CCP) Politburo Standing Committee - also reached out to Taiwan. "We are willing to work with any political parties, organisations, or individuals in Taiwan, regardless of their past stances, as long as they recognise the 1992 Consensus and affirm that the mainland and Taiwan are part of one China."

Compared with predecessors Jiang Zemin and Hu Jintao at similar memorials in 1996 and 2006 respectively, Mr Xi went on at greater length on the need to combat separatism. For instance, he mentioned the word "separatism" nine times, compared with twice in Mr Jiang's speech and none in Mr Hu's.

Observers say the higher emphasis on anti-separatism and on activities to commemorate Sun's birthday reflect the CCP's concerns over the state of cross-strait ties after Taiwan came under the rule of the pro-independence Democratic Progressive Party and its President Tsai Ing-wen refused to acknowledge the "one China" principle.

Musicals, exhibitions and nationwide symposiums on Sun's legacy were held to remember the founder of Kuomintang (KMT) who helped end imperial rule in China.

Cross-strait expert Wang Weinan of the Shanghai Academy of Social Sciences said the CCP sees a need to tap more on Sun as it views cross- strait ties to be in dire straits. "The mainland sees pro-independence sentiments becoming part of the mainstream discussion in Taiwan, and yet the counterforce, like the KMT, has become weaker with no rebound in sight soon," he told The Straits Times. "The CCP also sees Sun as someone that can be a unifying figure across the Taiwan Strait."

After losing the civil war to CCP, Sun's KMT fled in 1949 to Taiwan, where it ruled for decades before losing power in 2000. It won back power in 2008 and lost it this year.

Dr Wang said Mr Xi's speech also likely aimed to strike at separatists in Hong Kong, following a rare interpretation by Beijing last Monday of the city's mini-Constitution that effectively barred pro-independence legislators from taking office.

But Professor Shih Cheng-feng of Taiwan's National Dong Hwa University said there might be little impact in Taiwan from using Sun as a unifying figure as its youth "have a weak sense of history".

He said Mr Xi's strong warnings against Taiwan independence might also be counterproductive. "Actually, many people in Taiwan don't really support independence. But the more the CCP lectures against this, the more people think about it."