Police say an overdose death in southern Ontario has been linked to the deadly opioid carfentanil.

Toronto police have identified carfentanil in street drugs seized in the city for the first time, a day after officials confirmed the deadly synthetic opioid had been found in Ontario.

Street drugs seized by Ontario police have tested positive for carfentanil for the first time and experts are warning the potentially fatal opioid could contribute to more overdose deaths across the province.