President Xi Jinping reiterated his call for China to "reunite" with Taiwan, the self-ruled island China claims as its own, during an address on the eve of national holiday celebrations.
Xi also used his speech to thousands of people gathered for a banquet celebrating 75 years of the People's Republic to call for opposition to the "separatist activities" of supporters of Taiwanese independence.
"Achieving complete national reunification is the common aspiration of the Chinese people," Xi said.
"It is an irreversible trend, a matter of justice, and it is in accordance with the popular will. No one can stop the march of history," he said.
Beijing has said it will never renounce the use of force to bring Taiwan under its control and has also stepped up rhetoric about "unification".
The People's Republic of China was founded on October 1, 1949, after the Communist army defeated nationalist Kuomintang forces at the end of a civil war lasting two decades.
The defeated nationalists fled to Taiwan.
"Taiwan is sacred territory for China. People on both sides of the Taiwan Strait have blood ties, and these family ties will always be stronger than others," Xi said.
Taiwan's President Lai Ching-te rejects China's claim on the island and Beijing in turn regards him as a "dangerous separatist".
China has ramped up military and political pressure on Taipei in recent years, sending warplanes, drones and naval vessels around the island on a near-daily basis.
