China hit back at Canada over accusations it was probably behind a disinformation campaign aimed at a lawmaker who has taken a hard line against Beijing, renewing tensions between the nations.

Canada said Wednesday that the Chinese government was likely behind a series of “misleading narratives” that appeared on social media about Michael Chong, a Conservative who sponsored a motion in parliament declaring that Beijing’s treatment of Uyghurs and other ethnic minorities in Xinjiang amounted to genocide.

“Most of the activity was targeted at spreading false narratives about his identity, including commentary and claims about his background, political stances and family’s heritage,” Canada said. It added the campaign in May on WeChat involved “known state-media outlets and accounts that are likely linked to China’s state apparatus but whose linkages may be opaque.”

China’s embassy in Ottawa said in a statement Thursday that “the Canadian statement is complete nonsense and is outright slandering and smearing against China.” It added that “the Canadian side has continued to hype up various versions of the lie that China is interfering in Canada’s internal affairs but it has not produced any evidence.”

The exchange marks an escalation in the dispute between China and Canada over Chong and other matters dating back some five years. Canada expelled a Chinese diplomat in May after a newspaper report that he was looking into penalizing the lawmaker over his positions on Beijing, punishment that could entail sanctioning Chong’s relatives in Hong Kong. Hours later, China ordered a Canadian diplomat to leave the country.

See: Why Have Canada and China Kicked Out Each Other’s Diplomats? Q&A

Beijing-Ottawa ties started souring in 2018 when Canada arrested Huawei Technologies Co. executive Meng Wanzhou as part of a US-led extradition effort and China detained two Canadians on suspicion of spying. Meng and the Canadians have since been released.

In November, Chinese President Xi Jinping publicly confronted Canadian Prime Minister Justin Trudeau at a Group of 20 summit, accusing him of leaking details of a private meeting.

--With assistance from Xiao Zibang.