Four U.S. airlines have failed to satisfy China's aviation regulator over their website descriptions of Hong Kong, Macau and Taiwan.

China is asking foreign companies to avoid referring to Taiwan in particular as a country in its own right. Beijing policy dictates that China will refuse diplomatic relations with any country that recognizes the island as a sovereign state.

At present most sovereign states only hold official diplomatic recognition with the mainland People's Republic of China (PRC), designating it, with some ambiguity, as the sole representative of China. Just 17 of 163 United Nations formally hold diplomatic relations with Taiwan, also referred to as the Republic of China (ROC).

In May, Washington described the Chinese demands over Taiwan naming as "Orwellian nonsense" and requested talks on the matter. China refused to engage and set a deadline of July 25 for firms, especially airlines, to make the changes.

The Civil Aviation Administration of China (CAAC) said Thursday that 40 of 44 international carriers had satisfactorily amended their website references to Taiwan, as well as the former British colony of Hong Kong and the former Portuguese colony of Macau.

CAAC identifies the four outstanding airlines as United Airlines, American Airlines, Delta Air Lines, and Hawaiian Airlines. As of Thursday, all four websites for the airlines now only list Taipei's airport code but do not reference Taiwan.

The Chinese aviation body said that the remaining four airlines had submitted a two-week extension to audit their website, as full "rectification" had not been completed.

CAAC did not make clear what more is expected before it is fully satisfied with the change but said it would pay close attention before deciding to take action.

United Airlines, American Airlines, Delta Air Lines, and Hawaiian Airlines were not immediately available for comment.