China has exerted pressure on Mayday, a well-known rock band from Taiwan, to make pro-China remarks before Taiwan's crucial elections the following month.

An internal Taiwan security note seen by reporters revealed that Mayday had been invited to join China's "media propaganda on Taiwan" and publicly endorse Beijing's assertions that democratically governed Taiwan is a part of China by China's National Radio and Television Administration.

Taiwanese authorities had provided information on Chinese government activities to the note earlier this month.

As Beijing increases its political pressure to bolster its claims to sovereignty, Taiwanese celebrities find it harder and harder to succeed in the Chinese market, where Mayday is one of the most successful Taiwanese artists.

Following claims on Chinese social media that the band had lip-synchronized during one of their recent performances in China, the Chinese authorities announced in December that they were opening an investigation against Mayday. Two Taiwanese security officials who were looking into the matter are said to be putting pressure on the rock stars.

Requests for feedback from Mayday's management company, B'in Music, went unanswered. Claims that B'in Music lip-synced during the band's November tour in China — where the technique is forbidden — has previously been refuted.

Requests for comments were not answered by China's Taiwan Affairs Office or the Publicity Department, which is in charge of the country's radio and television administration.

Unspecified "political service" was requested by Chinese authorities, according to a person with direct knowledge of the matter who wished to remain anonymous, but the rock stars refused to comply.