Two Burlington men have been arrested in what police are calling the largest fentanyl seizure by Ontario law enforcement.

Provincial police say it began as an investigation into methamphetamine production in Durham and Halton.

They instead uncovered an fentanyl tableting operation.

Police say the drugs were being trafficked in both Ontario and British Columbia.

They say they seized more than 120,000 fentanyl pills and 70 kilograms of powder.

Halid Sefic, 30, and Edin Sefic, 34, of Burlington and Richard Atanasoff, 56, of Toronto face drug charges.