SEOUL (KOREA HERALD/ASIA NEWS NETWORK) - Girls' Generation member Tiffany upset South Korean fans on social media, where she posted a photo of a Tokyo Dome concert on Sunday, the day before South Korea marked the 71st anniversary of liberation from Japan's colonial rule.

The United States-born, South Korea-based star was denounced for using the Japanese flag emoticon in her post, as well as the rising sun flag that represents Japanese imperialism.

As the dispute seemed to get worse, the 27-year-old posted an apology on her Instagram on Monday: "I am sorry for causing trouble on such a meaningful day. I am very embarrassed and regretful about my mistake, I will be more considerate next time."

Despite her apology, anger from netizens persisted, with comments ranging from "Do you think a letter can solve everything?" to "Just leave Korea".

Over the weekend, Girls' Generation had performed at two joint concerts in Tokyo with other SM Entertainment singers.

An official at an entertainment agency recently warned celebrities about how they welcome National Liberation Day. As it is an important day for all Korean citizens, the slightest mistake can rile fans.

"Celebrities need to be more careful when they use social media. What seems to be nothing can trigger a bad outcome," the official was quoted by Chosun.com as saying.

In contrast to Tiffany, singers Jun Hyo Seong, Bada, girl group DIA, and actors Lee Ki Woo and Han Ji Min were praised for their patriotic posts.

Jun posted a photo on Instagram showing her wearing a butterfly bracelet that symbolises the Korean comfort women who suffered the tragic history of Japanese colonialism. She wrote: "It is National Liberation Day. Thank you, I will not forget."

Bada posted a clip on Instagram, saying: "Our current happiness is all due to the sacrifices of patriotic martyrs. I will live with gratitude."

Similarly, DIA, Lee and Han posted pictures of themselves with Korean flags and appreciative words.