The Chinese ambassador to the United Nations on Monday reiterated that Taiwan is an inalienable part of China's territory, adding that the one-China principle is "a red line" in China's relations with other countries, and China allows no one to cross it.

"China firmly opposes any separatist move towards 'Taiwan independence' and any interference by external forces and allows no room for 'Taiwan independence' in whatever form," Zhang Jun, China's permanent representative to the UN, told reporters at a news conference on the program of the work of the Security Council for the month of August in his capacity as president of the UN Security Council.

Zhang pointed out that China has repeatedly made clear to the US its serious concerns over US House Speaker Nancy Pelosi's pending visit to Taiwan as well as China's firm opposition to it.

"Such a visit is apparently dangerous and provocative. It will send a seriously wrong signal to the separatist elements seeking 'Taiwan independence', undermine the one-China principle, undermine China's sovereignty and territorial integrity, undermine the peace and stability in the Taiwan Straits, and undermine the relationship between China and the US," said Zhang.

"China is fully prepared to respond. If the US insists on making the visit, China will take firm and strong measures to safeguard its national sovereignty and territorial integrity, and the US has to bear all the serious consequences arising thereof," the envoy said.

The Taiwan question bears on China's core interests and is the most important and sensitive issue in China-US relations, the envoy pointed out.

"We noticed that in his July 28 phone call with President Xi, President Biden reiterated that the one-China policy of the US has not changed and will not change, and that the US does not support 'Taiwan independence,'" he said.

"We urge the US to honor its words, earnestly follow the one-China principle and the three China-US joint communiques, and work with China to resolutely oppose and contain 'Taiwan independence,'" Zhang said.

In response to questions comparing Pelosi's expected visit with the one by then-US House Speaker Newt Gingrich in 1997, Zhang said that "a previous mistake does not make the following mistake legitimate".

"In recent years, due to the influence of some external forces, the situation in Taiwan has changed for the worse, and the 'Taiwan independence' elements are moving down on the wrong path. Without prompt containment measures against them, the situation may risk losing control," said Zhang.

China has assumed the rotating presidency of the Security Council for August.

Zhang on Monday held the general consultations of the council, and the program of work for this month was adopted. At the following news briefing, he reported to the media the working arrangements of the council.

Zhang emphasized that China has been making unremitting efforts in advancing the UN development agenda.

The presidency of the Security Council is held by each of the council members in turn for one month. China last held the presidency of the Security Council in May 2021.