China has been ramping-up efforts to police language used to describe Chinese-claimed territories such as Taiwan.
The state-run Global Times newspaper said the map also omitted South Tibet and the South China Sea, and that the issue sparked a social media frenzy in China after a photo was posted of the shirt at an outlet store in Canada. In January, websites as well as apps for Marriott were blocked for more than week after the hospitality company listed Hong Kong, Macau, Taiwan and Tibet as individual countries in both emails as well as apps.
U.S. clothing retailer Gap has apologised to China over a T-shirt with a map showing the mainland but omitting Taiwan, becoming the latest foreign firm to run afoul of Beijing's policy on the self-ruling island.
The US retailer store has said its apology that it would implement "rigorous reviews" to prevent such things from happening again.
In a post on China's Weibo microblogging platform, the company said it discovered that some T-shirts it sold overseas "had an erroneous design of China's map".
"We sincerely apologize for this unintentional error", said the company, which issued the statement through its public relations firm APCO after making a similar apology late Monday on its Weibo account.
Lee also reiterated the government's stance on the matter, asking the airline not to belittle Taiwan or damage its sovereignty and dignity by bowing to pressure from China.
Delta Air Lines based in the US and Zara the European based clothing retailer were on the hot seat as well over issues of a similar nature on their e-commerce sites in China.
The name change came in the wake of letters sent by China's Civil Aviation Administration in late April, pressuring 36 American and worldwide airlines to remove references to Taiwan, Hong Kong and Macau as countries on their websites and marketing materials.
Fashion brand Zara and Delta Air Lines drew Beijing's ire and apologized for listing Taiwan and/or Tibet as countries on drop-down menus on their websites.
Taiwan's foreign ministry said it was "deeply concerned" about Air Canada's move to refer to Taiwan as part of China on the website.