China has blacklisted four of its citizens who staged a loud protest by singing the Chinese national anthem at a Bangkok airport two weeks ago, after a severe delay in their flight schedule. The China National Tourism Administration (CNTA) has stated that the blacklist status is punishment for the citizens' "uncivilized tourist behavior," reports NDTV News.

According to the CNTA, the tourists acted in an inappropriate manner after they refused to board a flight at the Don Mueang airport in Bangkok on Sept. 4. The Chinese tourists were originally set to leave the airport on the night of the Sept. 3. However, a 10-hour flight delay caused them to be moved to a flight that was set to leave on the morning of the 4th instead.

Frustrated, the Chinese tourists began to belt out a loud rendition of the country's national anthem, drawing the attention of numerous people in the airport. During the incident, 30 people were arrested, according to Mashable.

Four of those tourists have blacklisted. Though the status does not necessarily ban them from flying, it does give airlines and travel agencies every right to refuse them service.

China is known to assert a strong code of conduct around its national anthem, which has already been banned to be sung in weddings, funerals and commercial areas since December last year. The ruling Communist Party considers singing the national anthem at non-political celebrations a violation of the country's etiquette.

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