Beijing will not allow any "Taiwan independence" secessionist to split China, An Fengshan, spokesman for the State Council's Taiwan Affairs Office, said on Wednesday.

The comment came against the backdrop of recent visits to Taiwan by two officials from the United States after US President Donald Trump signed a bill called the Taiwan Travel Act, which encourages reciprocal visits between Taiwan and the US by officials at all levels.

Alex Wong, deputy assistant secretary of the US State Department's Bureau of East Asian and Pacific Affairs, visited Taiwan from March 20 to 22. Another US official, Ed Royce, the House Foreign Affairs Committee Chairman and a Republican, visited the island after Wong. The visits increased friction in cross-Straits relations.

Beijing opposes the travel act and has urged the US to adhere to the one-China policy, and it initiated negotiations on the issue to urge the US to adhere to the three joint communiques that lay out the two countries' mutual understanding.

"The mainland's major principle toward Taiwan is clear and consistent," An said in response to a China Daily question about "armed reunification".

"We will work in utmost sincerity and make our best effort to strive for peaceful reunification," An said. "Our determination to safeguard our country's territorial sovereignty is steadfast. We will not allow any 'Taiwan independence' force to separate the island from China."

President Xi Jinping delivered a speech on March 20 at the closing meeting of the first session of the 13th National People's Congress in which he vowed to defeat secessionist attempts. The speech was seen as a strong warning to Taiwan.

"Any actions and tricks to split China are doomed to fail. And these separatists' actions will be met with the condemnation of the people and the punishment of history," Xi said.

He also said that the Chinese people "have the resolve, the confidence and the ability to defeat secessionist attempts in any form".

An article about the tactics of Taiwan reunification by military force - written by Lieutenant General Wang Hongguang, a retired deputy commander of the former Nanjing Military Command of the People's Liberation Army - was published on the website of Global Times on Tuesday. Global Times is a subsidiary of People's Daily.

At the end of the article, Wang introduced what he said would be his next topic concerning military action: "Taking Taiwan in less than three days".

Zhu Songling, a professor of Taiwan studies at Beijing Union University, said, "Reunification cannot be stopped. It is China's domestic issue."

The signing of the Taiwan Travel Act "greatly harmed cross-Straits and China-US relations", Zhu said. "We should realize it is not a good sign, and should pay more attention at the tactical level."