Canada and India have expelled each other's diplomats amid an ongoing diplomatic row over the killing of a Sikh separatist leader in Canada. The tit-for-tat moves also took place last year.

The Canadian foreign ministry says it expelled six Indian diplomats for refusing to cooperate in the investigation of the killing of Sikh religious leader Hardeep Singh Nijjar.

Nijjar was shot dead in June last year outside a temple near Vancouver. He was a Canadian citizen and reportedly a supporter of the Sikh independence movement. New Delhi designated Nijjar as a terrorist in 2020.

Canadian Prime Minister Justin Trudeau said Monday the country's police have "clear and compelling" evidence that agents of the Indian government were involved in the killing.

India reacted harshly. Its foreign ministry expelled six Canadian diplomats on Monday, including the acting high commissioner, as a countermeasure.

Nearly 800,000 Sikhs live in Canada. New Delhi has been wary that their political influence could spark the independence movement of the minority Sikhs in India.