MONTREAL - Less than two weeks after easing restrictions, Quebec is reversing its decision to reopen gyms and high schools in the greater Montreal area.

Despite the fact that daily new cases in Montreal have remained relatively stable, Premier Francois Legault said Tuesday he is imposing new restrictions as a preventive measure.

Starting next Monday, students in grades 9, 10 and 11 in red zones, including Montreal, will attend school in person on alternate days and extracurricular activities will be cancelled. Legault said gyms in red zones must close as of Thursday, and that places of worship will have to limit attendance to 25 people.

The province will also ban residents of red and orange zones from travelling to yellow zones starting Thursday, according to the Health Department's website. That measure was not announced at the news conference.

“We haven't seen a strong increase in hospitalizations,” Legault said. “But we can think it will come in the next days and weeks. It's almost a question of math.”

Legault defended his decision to tighten restrictions so soon after they were loosened, saying public health recommendations have changed as a result of the spread of novel coronavirus variants.

“Put yourself in my place,” he told reporters. “Last week, public health told me we could reopen (secondary schools) full-time. I couldn't say, no, no, no, we'll leave them closed.”

He said he had hoped the reopening would last, but said the recommendations from public health changed within the span of one week. Allowing students back in classes full time to see their friends for one week was better than keeping them on alternative schedules, Legault said.

Health Minister Christian Dube announced COVID-19 vaccination appointments will be open to all Quebecers 60 and over by the end of the week, while those 55 and over will be able to book an appointment for an Oxford-AstraZeneca vaccine by Thursday.

Dube said officials will announce plans on Wednesday to vaccinate people with serious medical conditions and essential workers, including teachers, daycare workers and police officers.

The start of the overnight curfew in the Montreal area will remain at 9:30 p.m. Legault said, but he warned he “won't hesitate” to move it to 8 p.m. if case counts rise in the coming days.

The latest restrictions come after five municipalities in Chaudiere-Appalaches entered a lockdown Monday night, meaning residents have to abide by an 8 p.m. curfew and non-essential businesses and schools must close until at least next week. A similar lockdown was imposed last week in Quebec City, Levis and Gatineau.

Quebec's health minister earlier on Tuesday asked regional authorities to act quickly to shut down operations that aren't respecting COVID-19 health rules. Dube said the spread of more contagious variants justifies acting when there's good reason to believe the rules aren't being followed.

In a letter sent to regional health directors on Monday, Dube said the current powers granted under the province's Public Health Act stipulate it's not necessary to wait until an investigation is complete before closing a location.

Quebec reported 1,168 new cases of COVID-19 on Tuesday, the seventh straight day the province has reported more than 1,000 cases. Authorities reported four additional deaths linked to the virus, including one within the preceding 24 hours. Hospitalizations rose by 11 from the day before, to 514, the Health Department said, with 121 people in intensive care, a drop of two.

The regions with the most new cases were Montreal with 300, Quebec City with 290 and Chaudiere-Appalaches, south of Quebec City, with 114.

There are now 278.5 active cases per 100,000 people in Quebec City, making it the most affected region in the province on a per capita basis, according to the Institut national de sante publique du Quebec, the province's public health institute. Across the province, there are 121.6 cases per 100,000 people.

The institute said an additional 682 suspected cases of coronavirus variants of concern have been detected in Quebec, bringing the total to 11,709.