The Conservatives have written to the Prime Minister to demand that he clarify his position on the forced labour of the mainly Muslim Uyghur minority in China after a Liberal MP was accused of attempting to cast doubt on the existence of the practice.

Michael Chong, the Conservative foreign affairs critic, wrote to Mark Carney Friday asking him if his assessment is “that Uyghur forced labour has and is being used” in China.

He also asked him to clarify if, during his official visit to China in January, he pro-actively raised the issue of human rights. Mr. Chong also asked if Mr. Carney is committed to upholding trade agreements that require Ottawa to prevent the importation of products produced using forced labour.

Michael Ma, a Liberal MP who crossed the floor from the Conservatives in December, has been under fire for questions he asked of an expert during a meeting of the Commons Industry Committee on Thursday.

During the meeting, Mr. Ma asked Margaret McCuaig-Johnston, a senior fellow at the University of Ottawa, whether she had seen forced labour or if she was relying on hearsay. His questions came after she told the committee Thursday that electric vehicles are being made with Chinese aluminum products by slave labourers in Xinjiang, an area of China populated by Uyghurs.

Mr. Ma has since apologized and said he was referring to auto manufacturing in Shenzhen and not Xinjiang.

Uyghur-rights advocates reacted with dismay at Mr. Ma’s questions.

Rushan Abbas, Washington-based founder and executive director of the two-time Nobel Peace Prize nominated Campaign for Uyghurs, said Uyghur forced labour is well documented and UN experts said this year that the conditions may amount to enslavement.

“I am deeply alarmed by the remarks of Canadian MP Michael Ma, suggesting that if one has not personally seen forced labor in China, it cannot be true,” she said in a statement. “By that logic, every dictatorship could erase its crimes simply by hiding them well enough.”

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The House of Commons in 2021 passed a motion recognizing a Uyghur “genocide.”

Mehmet Tohti, executive director of the Uyghur Rights Advocacy Project, said in a text message that Mr. Ma has either “not done his homework or completely ignored the fact of atrocity crimes that Uyghurs are facing, including ongoing genocide, ongoing forced labour and transnational repression.”

Canada-Hong Kong Link, a non-profit organization, said in a statement that Mr. Ma’s call for “first-hand” testimony, when there are strict access restrictions imposed by the Chinese Communist Party, “reflects an approach often used to undermine credible human rights evidence and avoid accountability.”

On Thursday evening, Mr. Ma apologized for the tone of his questions that he said “inadvertently came across as dismissive of the serious issue of forced labour.”

“To be clear, my line of questioning referred to auto manufacturing in Shenzhen, China, and not in Xinjiang,” he said in a social-media post. “I regret this mistake and apologize to Ms. McCuaig-Johnston and my fellow committee members. I condemn forced labour, in all its forms.”

Ms. McCuaig-Johnston expressed dismay on Friday that a China-based news site had published a story approving of the MP’s line of questioning of her.

The Gauncha or “Observer network” news site, wrote about the exchange and included screen shots of the MP and the academic.

The media in China is subject to censorship by Chinese Communist Party, which has a central Propaganda Department.

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Ms. McCuaig-Johnston had testified before MPs that Chinese electric vehicles are being manufactured with parts from aluminum made by slave labourers in Xinjiang. She referred to research by Human Rights Watch and gave Mr. Ma a report to read after the committee meeting.

She said in an e-mail Friday that bauxite is shipped from other parts of China to Xinjiang where it is processed into aluminum by Uyghurs. That aluminum is sent to vehicle and parts companies in Xinjiang and other parts of the country to be put into the cars.

Ms. McCuaig-Johnston, a former senior federal public servant, said since December, 2024, she has been sanctioned by China for being a member of the Advisory Board of the Uyghur Rights Advocacy Project.

She said Mr. Ma’s questioning – and the ensuing coverage of it in China – was damaging to her reputation.

“This doesn’t just impune my credibility in Canada. The Chinese media have now presented the exchange with really vicious remarks about me and praise for Mr. Ma valiantly undermining my credentials and analysis,” she wrote in the e-mail.