China's military is learning from Russia's invasion of Ukraine that any attack on Taiwan would have to be swift to succeed, but the Taiwan Strait would make that challenging, the island's defence minister said on Friday.

The possible impact of the war on China's military thinking on Taiwan and how China might attack the island, which Beijing sees as sovereign Chinese territory, has been widely debated in official circles in Taipei.

Taiwan Defence Minister Chiu Kuo-cheng said the Chinese military would have taken notes from the Russian invasion of Ukraine, which began one year ago. Russia tried but failed to capture the Ukrainian capital, Kyiv, in the war's opening days.

"The Russia-Ukraine war has brought great lessons for them - they will definitely seek speed," Chiu told reporters on the sidelines of parliament in Taipei, referring to China's military.

He said even if Chinese forces were planning a speedy attack, they would face difficulties trying to take the island in a sudden move as they would have to cross the Taiwan Strait that separates the two.

"They would still have to overcome this," Chiu said. "It wouldn't be as fast as a week or two."

China has never renounced the use of force to bring Taiwan under its control and continues to mount almost daily military patrols near the island.

"I've said it before - as soon as the guns sound we will keep going to the end. But we absolutely will not provoke."

Taiwan's democratically elected government says only Taiwan's people have the right to decide their future.

While Ukraine has won widespread public support in Taiwan, and Taiwan's government has sent humanitarian aid, China has declined to condemn Russia.

The two countries announced a "no limits" partnership shortly before Russia launched what it calls its "special military operation" on Feb. 24 last year.

China has said that it is a "naked double standard" to seek to conflate the issues of Taiwan and Ukraine as the island has always been part of China and is entirely a domestic matter.

"Taiwan will continue to firmly support Ukraine," the island's president, Tsai Ing-wen, wrote on her Facebook page on Friday, to mark the first anniversary of the invasion.

"I believe that when people who love democracy unite, democracy and freedom will win." (Reporting by Ben Blanchard; Additional reporting by Sarah Wu; Editing by Sonali Paul, Robert Birsel)