China warned on Monday that its military will "not sit idly by" should United States House Speaker Nancy Pelosi visit Taiwan.

"The Chinese side is fully prepared for any eventuality," Foreign Ministry spokesman Zhao Lijian said at a regular news conference on Monday. "China will definitely take strong and resolute measures to safeguard its sovereignty and territorial integrity."

When asked what measures China will take if Pelosi visits Taiwan, Zhao said: "If she dares to go,then let's wait and see."

The warning came as Pelosi arrived on Monday in Singapore, the first stop of her Asian trip, which will also take her to Malaysia, the Republic of Korea and Japan. Although Taiwan is not on her itinerary, international media such as CNN quoted unidentified Taiwan and US officials as saying that she might visit the island.

China has expressed its strong opposition to the US to a potential visit by Pelosi to Taiwan.

During a phone conversation with US President Joe Biden last week, President Xi Jinping said that it is the firm will of the more than 1.4 billion Chinese people to resolutely safeguard China's national sovereignty and territorial integrity.

The will of the people cannot be defied and those who play with fire will perish by it, Xi said.

Zhao said that "it is believed the US must have been fully aware of the strong and clear message sent out by the Chinese side".

If Pelosi, who is second in the line of succession to the US presidency, visits Taiwan, it would be a gross interference in China's internal affairs, severely undermine China's sovereignty and territorial integrity and trample on the one-China principle, Zhao said.

The spokesman added that such a visit would severely threaten cross-Straits peace and stability and undermine China-US relations, thus leading to a very serious situation and consequences.

China urged the US side to honor the commitment made by Biden of not supporting "Taiwan independence" and not to arrange for Pelosi to visit Taiwan, he said.

Zhao also criticized the irresponsible remarks made by US National Security Council Coordinator for Strategic Communications John Kirby, who said at the White House on Friday that there's no reason for China and the US "to come to blows" should Pelosi visit Taiwan.

"Since the US has recently started to stress the need to uphold a country's sovereignty and territorial integrity, we hope the US will first honor its words on the Taiwan question and stop applying any double standard," Zhao said.

The People's Liberation Army's Eastern Theater Command posted a video on its social media platform on Monday, saying that the Chinese military is fully prepared for any eventuality, and will act upon the order to fight and bury all invaders. The military will fight to the end for victory, it said.

Also on Monday, China's Qinglan Maritime Safety Administration in Hainan province issued a statement saying that military training exercises would take place in designated waters of the South China Sea from Tuesday to Saturday and the passage of any vessel that is not associated with these activities will be prohibited.

When meeting with Pelosi on Monday, Singapore Prime Minister Lee Hsien Loong highlighted the importance of stable US-China relations for regional peace and security.

Andrew Korybko, a Moscow-based analyst of US politics, said that there's no legitimate reason for any US representative, let alone one as prominent as Pelosi, to visit the Taiwan region.

"The vast majority of the international community, including the US, recognizes the island as an integral part of China. To continue talking about traveling to Taiwan is therefore extremely disrespectful to this major country and goes against basic diplomatic decorum," he said in an opinion piece published on the website of the China Global Television Network.