Hong Kong's flag carrier Cathay Pacific became the latest airline to list Taiwan as part of China on its website on Wednesday after a request from mainland authorities.
The Chinese Civil Aviation Administration sent a notice to dozens of airlines in April asking them to comply with Beijing's standards.
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.
Smaller operators Hong Kong Express and Hong Kong Airlines also switched their listings to "Taiwan, China" on their English and Chinese sites.
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.
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.
That comes despite a White House statement in May that called China's demands "Orwellian nonsense".
A growing number of international airlines, including Qantas and Singapore Airlines, had already changed their website classifications of Taiwan to "Taiwan, China". (AFP)