China on Wednesday dismissed comparisons between the Ukraine crisis and its own claim over Taiwan, after the self-ruled island's president said evidence of Russian aggression was being used to hurt Taiwanese morale.

Democratic Taiwan has watched the Ukraine situation closely as it lives under constant threat of a Chinese invasion, with Beijing claiming sovereignty over the island and vowing to seize it one day -- by force if necessary.

Taiwanese President Tsai Ing-wen said Wednesday "external forces" were "attempting to manipulate the situation in Ukraine and affect the morale in Taiwan's society", and urged the government to be "more vigilant against cognitive warfare".

Beijing said any comparison showed a "lack of the most basic understanding of the history of the Taiwan issue".

"Taiwan, of course, is not Ukraine," foreign ministry spokeswoman Hua Chunying said at a regular press conference.

"Taiwan has always been an inalienable part of China's territory. This is an irrefutable historical and legal fact," she said, blasting "unwise" Taiwanese authorities for "making the Ukraine issue into a hot topic".

Earlier, Tsai said: "Our government condemns Russia's violation of Ukraine's sovereignty... and urges all parties to continue to resolve the disputes through peaceful and rational means."

Taiwan President Tsai Ing-wen has condemned Russia for ordering troops into rebel-held regions in Ukraine
Taiwan President Tsai Ing-wen has condemned Russia for ordering troops into rebel-held regions in Ukraine AFP / Sam Yeh

Beijing has ramped up military, diplomatic and economic pressure on Taiwan since Tsai came to power in 2016, as she rejects the stance that the island is Chinese territory.

Taiwan's defence ministry said last year that China had launched a disinformation campaign aimed at seizing the island "without a fight".

Tsai on Wednesday also told national security and military units to remain vigilant and step up surveillance of military activities around Taiwan.

The final quarter of 2021 saw a massive spike in incursions by Chinese warplanes into Taiwan's air defence identification zone.

Last year, Taiwan recorded 969 such incursions, according to a database compiled by AFP -- more than double the roughly 380 in 2020.

Beijing has trod a cautious line on Ukraine but also offered growing support to Russian President Vladimir Putin.

The two powers signed a joint statement this month, agreeing on multiple foreign policy goals including no further expansion of NATO and that Taiwan is an "inalienable part of China".

Chinese officials have also repeatedly sided with Russia in blaming the West for the tensions over Ukraine, accusing them of a "Cold War mentality" while describing Moscow's security concerns as "reasonable".