The grueling struggle over royalties between Universal Music Group and TikTok took on a new and more serious dimension in the early hours of Tuesday, when songs published by UMG began to disappear from the platform.

The stalemate, which began earlier this month, first resulted in the removal of UMG-owned or distributed tracks from the platform, but it has now expanded to include music published by the firm.

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The situation, backed by a bellicose war of words from both sides, sets UMG, the world’s largest music corporation, against TikTok, the most influential platform for promoting music for the past five years, as they continue to refuse to renew their licensing arrangement, which expired on January 31.

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This latest action has a wide-ranging impact, affecting a large number of recordings not released by a UMG-owned label, as well as many artists who have collaborated with songwriters under contract with Universal Music Publishing Group. Videos featuring those tunes must be removed from the platform or muted.

While the breadth of the move is extensive, with artists and songwriters potentially having various deals in different areas, Variety reports that the initial focus is on “Anglo-American” material. Adele, Justin Bieber, Mariah Carey, Ice Spice, Elton John and Bernie Taupin, Metallica, Metro Boomin, Harry Styles, Taylor Swift, SZA, the Weeknd, and many others are among the top authors on UMPG.

Given the large number of songwriters and publishers credited on most contemporary hit songs, it was unclear how much music would be impacted, or where the two companies might draw the line on whether or not a song is controlled by UMPG — for example, if one of seven writers on a song is under contract with Universal. Opinions differ greatly: sources close to UMG claim that it owns the bulk of the songs on the platform, while those close to TikTok believe the figure is far lower, between 20% and 30%. According to the latter sources, TikTok’s user base has not decreased since the removal of UMG music earlier this month.

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In an open letter dated Jan. 30, UMG chairman-CEO Lucian Grainge stated, “In our contract renewal discussions [with TikTok], we have been pressing them on three critical issues: appropriate compensation for our artists and songwriters, protecting human artists from the harmful effects of AI, and online safety for TikTok’s users…” In terms of artist and composer compensation, TikTok proposed paying our artists and songwriters at a fraction of the rate that similarly positioned major social platforms pay,” noting that TikTok accounted for 1% of the company’s overall income. “Ultimately TikTok is trying to build a music-based business, without paying fair value for the music.”

TikTok responded with an open letter, stating that Universal Music Group prioritized their own profit over the interests of their artists and composers. TikTok has successfully reached ‘artist-first’ agreements with every other label and publisher. Clearly, Universal’s self-serving tactics do not benefit artists, songwriters, or fans.

More heated remarks are expected during UMG’s results call on Wednesday.

Despite UMG’s claim about revenue, the move has had a significant impact on artists and composers, as they have lost the most potent platform for promoting their music, as well as any royalties that would have been produced on the site.

“That really hurts,” says songwriter-artist Bonnie McKee, who has written hits for Katy Perry and Britney Spears and will release a solo album in May. “TikTok is how musicians promote new songs, and now they’re muting someone’s entire catalog? The labels say TikTok is so vital and push their artists to [use the platform], but now they can’t?”

Sources close to the matter told Variety that the deadlock is unlikely to be resolved quickly. The clearest example occurred between 2008 and 2009, when Warner Music Group deleted or muted their music off YouTube for several months until the firms reached an agreement. However, the conflict between UMG and TikTok is far bigger in scope.

UMG and TikTok representatives did not immediately respond to demands for additional information on Tuesday. Variety will have more information as the situation develops.