"We see the situation abroad, and we're afraid and concerned with what could happen to Canadians who would choose to go abroad in the next few weeks," said Jean-Yves Duclos, Canada's health minister, during a news briefing Wednesday.

"The situation abroad is already dire in many places, and it's going to get worse very quickly. So we are afraid for what could happen to them if they chose to travel. And once they have left Canada, there is very little we can do to help them," he said.

While Canadian government officials indicated that other restrictions may be announced in the coming days, the US-Canada border remains open and those traveling by land do not need to provide a negative Covid-19 test if their trip is shorter than 72 hours and they are fully vaccinated.

In addition, Canada is still allowing foreigners to enter for business and leisure, provided they are vaccinated and provide a negative Covid-19 test upon entry.

Stricter travel measures could still come

Officials said they could not rule out imposing stricter measures in the days to come. The current advisory will last for at least four weeks.

"We are constantly reassessing so when we feel we need to change our policies, we will announce it as quickly as possible, but for now, we are monitoring it and assessing it," said Transport Minister Omar Alghabra during the news conference.

Public health officials have warned in recent days that Canadians remain vulnerable to the Omicron variant despite high levels of vaccination and that a rapid increase in Covid-19 cases in Canada was a possibility in the coming weeks.

'Rising threat of Omicron'

"I know the rising threat Omicron poses is not something any of us want to be dealing with, especially now just before the holidays. I know we are all tired, we are all tired of Covid. But I think we all also understand that after 21 months of fighting this virus and doing a pretty good job as a country, that making hard decisions quickly and behaving carefully pays off," said Deputy Prime Minister Chrystia Freeland when announcing the travel advisory.

Canada's booster rollout is ramping up in many provinces. Federal officials saying there are about 16 million doses on hand with more to come. Federal ministers indicated that the supply of booster doses would last for at least a few weeks.