Chinese leader Xi Jinping warned US President Joe Biden against playing with fire over Taiwan in a call last week but three sources told Reuters on Tuesday Pelosi was still set to visit the island.

"We cannot say for sure right now whether she will or will not get there, but everything about this tour and the possible visit to Taiwan is purely provocative," Kremlin spokesman Dmitry Peskov told reporters.

Maria Zakharova, Russia's foreign ministry spokeswoman, said the expected visit was a provocative attempt by Washington to pile pressure on China - with whom Russia has forged a strong partnership in recent years.

"We consider a possible visit by Pelosi to Taiwan ... as another provocative action by the United States aimed at exerting additional pressure on Beijing," she said.

"Russia confirms the principle of 'one China' and opposes the independence of the island in any form," Zakharova said.

China views visits by US officials to Taiwan as sending an encouraging signal to the pro-independence camp on the island.

Washington does not have official diplomatic ties with Taiwan but is bound by US law to provide the island with the means to defend itself.

In the Chinese civil war, Mao Zedong's Communists defeated the forces of the Kuomintang, or nationalist party, under Chiang Kai-shek, forcing him to flee to Taiwan in 1949.

China has repeatedly warned Pelosi against going to Taiwan, which it claims as its own.

Beijing says a Pelosi visit would contravene the 'one China' principle that Washington has vowed to abide by.

Australian Associated Press