Hong Kong's flag carrier Cathay Pacific and major American airlines moved to comply today with Beijing's demand that they list Taiwan as part of China, sparking anger on the self-governed island.

Taiwan condemned what it called the "insolent actions" of Beijing which it said was wielding its political and economic clout to pressure international firms.

"Taiwan's existence in the international community is an objective fact. It will not disappear because of suppression by Chinese authorities," Taiwan's foreign ministry said.

Taiwan is a self-ruling democracy but Beijing sees it as part of its territory, to be reunified by force if necessary, and is pushing to isolate the island on the international stage.

The Chinese Civil Aviation Administration sent a notice to dozens of airlines around the world in April asking them to adhere to Beijing's standards, setting a deadline of Wednesday to make changes.

Cathay Pacific and subsidiary Cathay Dragon had previously listed Taiwan as its own entity, but as of Wednesday morning, the island was listed as "Taiwan, China" on both its English and Chinese language websites.

Asked about the move, Cathay said its airlines were registered as part of "the Hong Kong Special Administrative Region (HKSAR) of the People's Republic of China".

"We must comply with the regulations and requirements of the relevant civil aviation authorities," it added in an emailed statement.

American Airlines spokeswoman Shannon Gilson said: "Like other carriers, American is implementing changes to address China's request. Air travel is a global business, and we abide by the rules in countries where we operate," in an email statement to AFP.

That comes despite the White House slamming China's demands as "Orwellian nonsense" in May.

Bloomberg News reported that four US carriers -- American Airlines, United Airlines, Delta and Hawaiian Airlines -- planned to change their websites over the coming days, citing a source familiar with talks.

American Airlines and Delta Air Lines still mentioned "Taiwan" as an entity on parts of their websites Wednesday, but the name had been wiped from some searches.

A simple arrival or departure airport search on American Airlines listed Taipei and Kaohsiung without any reference to Taiwan. Its destination listings usually follow the template of city name, then country name.

Some searches on Delta's website showed no country references for destinations in Taiwan, mainland China or semi-autonomous Hong Kong Wednesday, listing them simply by their city names.

Smaller airline operators Hong Kong Airlines and Hong Kong Express switched their listings to "Taiwan, China" on their English and Chinese sites.

A growing number of international airlines, including Qantas and Singapore Airlines, had already changed their website classifications of Taiwan to "Taiwan, China".

As relations between Beijing and Taipei deteriorate under Beijing-sceptic President Tsai Ing-wen, China is ramping up military and diplomatic pressure on Taiwan. It has also used its political and economic clout to woo away several of Taiwan's few remaining official allies.

Taiwan's cabinet spokeswoman Kolas Yotaka called China's behaviour "unjust" and asked for support from the international community.

"We keep on urging the international community not to become an accomplice of China bullying Taiwan," Kolas told reporters Wednesday.