Premier Francois Legault told reporters at a briefing on Tuesday that the proposal, details of which were still being finalised, would not apply to those who cannot get vaccinated for medical reasons.

Unvaccinated people put a financial burden on others and the provincial finance ministry is determining a "significant" amount that unvaccinated residents would be required to pay, Legault said, adding that such an amount would not be less than C$100 ($79.50).

Governments globally have imposed movement restrictions on the unvaccinated and few have levied fines on the elderly, but a sweeping tax on all unvaccinated adults could be a rare and controversial move.

While such a tax could be justified in the context of a health emergency, McGill University medicine and health sciences professor Carolyn Ells said, whether it survives a court challenge would depend on the details.

But Ells expressed surprise that the government was taking such a "dramatic" step now, when options such as further expanding vaccine mandates remain.

Provinces across Canada are tackling an exponential rise in COVID-19 cases that has forced tens of thousands of people into isolation and burdened the healthcare sector.

The highly transmissible Omicron variant has made it difficult for restrictive measures to curb the spread and health experts have stressed the importance of getting double and tripled vaccinated.

Quebec has been one of the worst-hit, regularly recording the highest daily count of coronavirus cases of all provinces and having several thousand healthcare workers off their jobs.

"The vaccine is the key to fight the virus. This is why we're looking for a health contribution for adults who refuse to be vaccinated for non-medical reasons," Legault said.

Legault said that even though the province has about 10% unvaccinated people, they account for about 50% of those in intensive care units.

Legault and his CAQ party face a provincial election in October.

On Monday, Canadian Prime Minister Justin Trudeau said that the federal government had secured enough COVID-19 vaccine doses for all eligible Canadians to receive a booster as well as a fourth dose.

Last month, Quebec said it had "no choice" but to allow some essential workers to continue working even after testing positive for COVID-19 to prevent staff shortages from impeding its healthcare services. It has also imposed curbs on gathering.

($1 = 1.2578 Canadian dollars)