Canada's top doctor says urgent action is needed to curb the spread of Omicron, which is now the dominant strain of COVID-19 in several provinces.

Chief public health officer Dr. Theresa Tam said Wednesday there were more than 11,300 new infections nationwide the previous day, up from the average of 5,000 cases per day last week.

She said modelling shows case counts could be "very high" by early January.

On Wednesday evening, Quebec Premier Francois Legault announced new restrictions, saying the province had seen 9,000 new COVID-19 cases that day. Those numbers are expected to be recorded today.

As of Boxing Day, he said, private gatherings in the province will be limited to six people or two-family bubbles.

Restaurants, which are already operating at half capacity and have to close at 10 p.m., will also have to limit groups at tables to six people or two families.