TORONTO -- Ontario health officials are warning mine workers who returned from Nunavut this month that they may have been exposed to COVID-19.

Speaking to reporters on Monday afternoon, Associate Medical Officer of Health Dr. Barbara Yaffe said that more than 120 positive cases of the novel coronavirus were detected in workers at Mary River Mine, located in the Qikiqtani region of North Baffin.

There are about 1,000 workers at the mine, and Yaffe said that about 300 are from Ontario.

“It’s a fly-in site, people fly in for a few weeks then they go back home,” she said. “We are aware of a small number of cases already that have occurred in those workers that have returned to Ontario.”

“We are aware of the workers that had come back to 33 of the 34 public health units, so it’s pretty much the whole province.”

Most of the COVID-19 cases were identified on site, Yaffe said.

Anyone who worked at the mine and has returned to Ontario since April 30 is being urged to self-isolate immediately and contact public health officials.

“While every effort is being made by our local health units to contact and investigate all potential cases, there are concerns that not all of the mine workers have been identified and they may not be aware of their high risk status.”

Officials say the outbreak at Mary River Mine does involve the B.1.617.2 variant, originally found in India.