Trade unions and online safety experts have urged MPs to investigate TikTok’s plans to make hundreds of jobs for UK-based content moderators redundant.

The video app company is planning 439 redundancies in its trust and safety team in London, leading to warnings that the jobs losses will have implications for online safety.

The Trades Union Congress, Communication Workers Union and leading figures in online safety have signed an open letter to Chi Onwurah MP, the Labour chair of the science, innovation and technology committee, calling for an investigation into the proposals.

The letter warns the cuts could expose children to harmful content, citing estimates from the UK’s data watchdog that up to 1.4 million TikTok users are under 13. TikTok has more than 30 million UK users.

“These safety-critical workers are the frontline of protecting users and communities from deepfakes, toxicity and abuse,” the letter said.

It also claims that TikTok is looking to replace the moderators with artificial intelligence-driven systems and with workers in countries such as Kenya and the Philippines.

How TikTok harms boys and girls differently – video

How TikTok harms boys and girls differently – video

The signatories also accuse Chinese-owned TikTok of union-busting by announcing the job cuts eight days before workers were due to vote on union recognition with the CWU’s tech branch.

“There is no proper business case for making these redundancies. TikTok’s revenues are booming – with a 40% increase for the UK and Europe alone,” the letter said. “Yet the company has decided to cut corners. We believe this decision is an act of union-busting – at the cost of workers’ rights, user safety and the integrity of online information.”

The letter is also signed by Ian Russell, the father of Molly Russell, a British teenager who took her own life after viewing harmful content online, the Meta whistleblower Arturo Bejar and Sonia Livingstone, a professor of social psychology at the London School of Economics.

It asks the committee to examine the implications of the redundancies for online safety and workers’ rights and what legislative steps can be taken to prevent offshoring of content moderation or replacing human moderators with AI.

Asked to comment on the letter, Onwurah said the jobs cut plans indicated that TikTok’s commitment to content moderation was under review, which “given the clear role that the recommendation algorithms used by TikTok and other platforms play in exposing users to large volumes of harmful and misleading content is a matter of significant concern”.

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Onwurah said the planned redundancies jarred with TikTok’s recent appearance in front of her committee in which the company outlined its commitment to keeping the platform safe in terms of financial investment and personnel.

She said: “TikTok told the committee of its commitment to upholding the highest standards in protecting both its users and its employees. How does this announcement align with that commitment?”

A TikTok spokesperson said: “We strongly reject these claims. We are continuing a reorganisation that we started last year to strengthen our global operating model for Trust and Safety, including concentrating our operations in fewer locations globally, ensuring we maximise effectiveness and speed as we evolve this critical function for the company with the benefit of technological advancements.”

According to TikTok, the company has been engaging with the CWU voluntarily and has offered to continue discussions with the union once the current redundancy consultation has concluded.