Popular Taiwanese rock band Mayday is being investigated by Chinese authorities over allegations of lip-synching during recent concerts, an accusation the band’s label has denied in a controversy that has dominated Chinese social media since the weekend.

The accusations centered on Mayday’s recent shows in Shanghai, where it performed eight times over 10 days in mid-November, to a combined audience of more than 360,000 fans.

The band, which has been going for more than two decades and is sometimes dubbed the “Asian Beatles,” boasts a huge fan base in China, where its shows often sell out quickly.

The Shanghai Culture and Tourism Bureau, a municipal government department overseeing commercial performances, said it attached great importance to the public backlash against the “lip-synching” claims and had required the concert organizer to cooperate with an investigation, state news agency Xinhua reported Monday.

In a statement on Monday evening, Mayday’s record company B’in Music dismissed the online accusations as “malicious attacks, rumors and slander,” saying they had seriously damaged the band’s image.

“Our company is actively cooperating with relevant law enforcement authorities to carry out investigations. We believe the relevant authorities will give us a fair result to set the record straight,” said the statement posted on Chinese social media site Weibo.

Live shows routinely use pre-recorded background vocals and music to bolster artists’ live singing performances, especially acts that involve vigorous choreography.

Chinese government regulations explicitly ban performers from “deceiving audiences with lip-synching,” and organizers from arranging for performers to lip synch. Violators can face a maximum fine of 100,000 yuan (about $14,000). A government guideline on how the regulations should be implemented defines lip synching as “using pre-recorded songs in place of live singing.”

The controversy started last Thursday when a music vlogger on Bilibili, one of China’s biggest video-sharing platforms, posted a video in which he used computer software to analyze the vocals of 12 songs recorded live by a fan at Mayday’s concert in Shanghai on November 16.

The vlogger claimed his analysis found the band’s lead singer, Ashin, lip synced at least five songs during the three-hour gig, saying the vocalist’s singing was precisely in tune for those numbers, while drifting in and out of pitch drastically in the other songs.

The vlogger’s allegations quickly gained traction on Weibo. By Sunday, the controversy had become the top trending topic, garnering more than 300 million views.

Some Mayday fans said they were disappointed, while others defended the band, including by posting snippets of their live performances where Ashin could be heard clearly singing out of tune.

State broadcaster CCTV reported Monday that video and audio recordings of Mayday’s concerts in Shanghai had been submitted to local authorities for “scientific evaluation and analysis,” and that the result would be announced.

Mayday primarily sings in Mandarin with some songs in the Hokkien dialect.

Their songs are catchy and addictive, happy-go-lucky, pop-infused anthemic rock, akin to U2 or One Direction. And with titles like “Party Animal,” “Cheers” and “Here, After Us,” they project the innocence of a younger generation, with all its accompanying hope and heartbreak.

The band is well known for hosting energetic marathons of music, with each show typically lasting two to three hours.

Since their debut in the late 1990s, the band has captured a following not only among millennials but also with a youthful fanbase of gen-Zs who are almost half its members’ age.

Other artists from Taiwan have encountered difficulties in China for being outspoken about the self-governing island, which Beijing views as its own territory. But Mayday has largely steered clear of politics and maintained huge popularity among mainland Chinese.

They were among the first Taiwanese musicians to hold large-scale concerts in China after the country lifted its stringent zero-Covid policy and travel restrictions.

In May, when Mayday’s concerts in Beijing went on sale, nearly 300,000 tickets for six shows were sold out within five seconds, Chinese state media reported at the time.