China's President Xi Jinping said Saturday "peaceful reunification" with Taiwan "will be and can be realised", days after Chinese warplanes made record incursions into the air defence zone of the democratically ruled island.

Self-governed Taiwan, which has never formally declared independence, lives under the constant threat of invasion by China, which views the island as its territory and has vowed to one day seize it, by force if necessary.

"Realising national reunification by peaceful means best serves the interests of the nation as a whole including our brethren in Taiwan," Xi said in a speech marking the 110th anniversary of a revolution that ended millennia of imperial rule and led to the founding of the Republic of China.

"Taiwan independence is the biggest obstacle to the reunification of the motherland and a serious hidden danger," Xi warned.

A large portrait of Sun Yat-sen, a Western-educated doctor who led the 1911 revolution that toppled the Qing empire, towered over the stage as Xi spoke.

Sun founded the Republic of China, which remains the formal name of Taiwan, where defeated Nationalists fled after Mao Zedong's Communist forces won the Chinese civil war in 1949 and established the People's Republic.

"The complete reunification of our country will be and can be realised," Xi said.

He also warned against foreign interference in Taiwan after a Pentagon official confirmed US special operations forces have been quietly training Taiwanese troops for months.

"The Taiwan issue is purely China's internal affair and does not allow any external interference," he said.

Beijing has ramped up pressure on Taipei since the 2016 election of President Tsai Ing-wen, who views the island as "already independent".

Tsai is scheduled to speak Sunday at an event commemorating the 1911 revolution, one of the few events that unite China and Taiwan.

Taiwan's defence minister said Wednesday that military tensions with China were at their highest in four decades, after around 150 Chinese warplanes -- a record number -- made incursions into Taiwan's air defence zone in recent days.

Xi's warning comes after Britain last week sent a warship through the Taiwan Strait, challenging Beijing's claim to the sensitive waterway, and a French delegation visited Taiwan despite warnings from China.