Raef Badawi, who could receive a round of 50 lashes on Friday, is suffering from hypertension and more flogging could weaken him further, his wife told reporters and lawmakers in Ottawa.
"Raef's health condition is bad and it's getting worse. I am very concerned about him," said wife Ensaf Haidar, who sought asylum in Canada's French-speaking province of Quebec with her three children after Badawi was jailed in June 2012.
"It is impossible for a human being to withstand 50 lashes every week," she added, surrounded by representatives from the Amnesty International charity.
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Badawi, also sentenced to 10 years in prison, is expected to have 20 weekly whipping sessions until his punishment is complete.
He received the first 50 lashes outside a mosque in the Red Sea city of Jeddah on January 9. Two subsequent sessions were postponed due to health concerns.
Haidar urged Canadian Prime Minister Stephen Harper to press Saudi authorities to release her husband.
Liberal lawmaker Irwin Cotler, Badawi's international legal counsel, denounced what he called "a standing violation of Saudi Arabia's obligations under international law, a frontal assault on the fundamental freedoms of religion and speech."