The Global Times newspaper on Thursday singled out Delta Air Lines , United Airlines , American Airlines and Hawaiian Airlines in a report which said that the companies had yet to meet requirements set by China's aviation regulator.
China has demanded that foreign firms, and airlines in particular, do not refer to self-ruled Taiwan as a non-Chinese territory on their websites, a demand the White House slammed in May as "Orwellian nonsense."
The Civil Aviation Administration of China (CAAC), which has been pushing airlines to make the change, had originally set a deadline for July 25. However, it said last month that the four U.S. airlines had asked for another extension as it perceived their amendments as "incomplete".
It was unclear what the exact deadline was in view of the time difference between the United States and China or what additional amendments the U.S. carriers were making.
Checks on Thursday showed Delta, United and American Airlines now list only Taipei's airport code and city, but not the name Taiwan, while there is no mention of Taipei or Taiwan on Hawaiian Airlines' website.
"United Airlines has begun to roll out changes to its systems to address China's requirements," a company spokesman told Reuters.
"United abides by and respects local laws and regulations in all markets and jurisdictions where we operate and conduct business. United flights to mainland China, Hong Kong and Taiwan will continue to operate normally."
Delta said that it, and other U.S. carriers, were "in the process of implementing website changes" in response to the CAAC's request. It added that it remained in close consultation with the U.S. government throughout the process.
Shannon Gilson, a spokeswoman for American Airlines said: "Like other carriers, American is implementing changes to address China's request."
Hawaiian Airlines, Airlines for America, a trade group which represents major U.S. carriers, and the CAAC did not immediately respond to requests for comment.
The Global Times reported the CAAC as saying that it was closely monitoring the situation.
It is unclear how China might punish airlines that did not comply with its requests, but in December it added a clause to rules governing foreign airlines in the country, saying regulators could change a company's permit if it did not meet "the demand of public interest".
Taiwan is China's most sensitive territorial issue. Beijing considers the democratic island a wayward province of "one China". Hong Kong and Macau are former European colonies that are now part of China but run largely autonomously.
(Reporting by Brenda Goh in SHANGHAI and Tracy Rucinski in CHICAGO; Editing by Simon Cameron-Moore)