Taiwanese politicians came out in support Saturday of a teenage pop star who was forced to apologize for waving the island's national flag on a South Korean television program, reigniting the complex issue of national identity on a day when voters are electing a new independence-leaning president and national legislature.

Outgoing President Ma Ying-jeou and candidates from the ruling and opposition parties united behind 16-year-old Chou Tzu-yu — whose stage name is Tzuyu. She posted an online video on Friday in which she bowed and said she had "always been proud to be Chinese."

The apology came after her South Korean management company said it was curtailing her commercial activities on the Chinese mainland, apparently in response to online commentary in China accusing her of supporting Taiwan independence. The company worried about offending China, which claims Taiwan as its own territory and objects to all expressions of the island's independent identity, including its flag and anthem.

Speaking to reporters, Ma said Tzuyu had nothing to apologize for.

"She did nothing wrong," Ma said. "This is unjust and unacceptable."

Ma said Taiwan's representative office in South Korea would pursue the matter with Tzeyu's management company, JYP.

In a protest statement, the Cabinet agency responsible for ties with Beijing said China needed to recognize the negative effect such developments have on Taiwanese sentiments toward the mainland.

"We hope the mainland will take this matter seriously, restrain public behavior and not allow relations between the sides to be affected by this," the Mainland Affairs Council said.

The agency's Chinese counterpart, the Cabinet's Taiwan Affairs Office, responded with a statement saying that "some political forces in Taiwan" were exploiting the situation to damage feelings toward the mainland.

"We support artistic exchanges between the sides and consistently encourage exchanges between young people from the two sides," the office said.

The leading candidate for the presidency, Tsai Ing-wen of the pro-independence Democratic Progressive Party, accused China and other critics of bullying Tzuyu.

"This has hurt the feelings of all Taiwan's people. A show of patriotism should never be opposed," Tsai said.

Online commentators compared Tzuyu's video apology to hostage clips posted by the Islamic State group. Wearing a turtleneck sweater and standing against a white tile background, Tzuyu said there was only one China and the two sides of the Taiwan Strait were "a single entity."

South Korea's entertainment industry draws heavily on the Chinese market for appearances and endorsements and is highly adverse to political controversies. China has used commercial pressure in the past to punish Taiwanese entertainers seen as backing the island's government, most notably in the case of singer Ah-Mei, who was banned after performing the national anthem at the 2000 inauguration of President Chen Shui-bian.

Nationalist sentiments dominate Communist Party-controlled social media in China, where online postings Saturday dismissed Tzuyu's apology as insincere.

"Regardless of your public relations efforts, the one-China policy is there, no more, no less, and cannot be challenged," the party mouthpiece People's Daily said on its official microblog.

China and Taiwan split amid civil war in 1949 and Beijing continues to claim the island as its own territory to be recovered by force if necessary. Although Taiwan's Nationalists and the DPP differ over Taiwan's ultimate fate, the Tzuyu issue prompted a rare show of unity across the political spectrum.