Further restrictions are being placed on international travel into Scotland after a new Covid-19 variant was identified in Brazil.
Travel corridors will be suspended from 04:00 on Monday.
That means all passengers travelling to Scotland from outside the Common Travel Area must self-isolate for 10 days.
They must also have a valid negative Covid test result, taken no more than three days before the scheduled time of departure.
Similar restrictions are being brought in across the UK.
Scottish Transport Secretary Michael Matheson said: "International travel has played a key role in previous waves of coronavirus and is a significant risk to our efforts to suppress the virus to the lowest possible level.
"The emergence of these new variants mean we must think carefully about restrictions on travel.
"It is crucial we take the right steps to prevent importing new strains that can increase transmission or undermine the vaccine in Scotland."
Travelling to or from Scotland without a reasonable excuse is already against the law.
While some exceptions remain where people are travelling for essential reasons, that list of exemptions will be tightened.
The Common Travel Area covers the UK, Republic of Ireland, the Channel Islands and the Isle of Man.
Scotland's National Clinical Director, Prof Jason Leitch, told the BBC's Drivetime programme, said it had been a four-country decision to suspend the exemptions to the quarantine rule.
"We are now suspending those travel corridors partly because of our nervousness about variants around the world," he said.
"To be clear just now we are exporting the virus to other places, we are not importing the virus. We have a very high prevalence across the UK and other countries are closing their borders to us.
"But importation is still a risk and it's a big risk if we get our numbers down."
He acknowledged that it would be "very difficult" for people who are overseas or were planning to go abroad.
But he added: "Remember, the law in Scotland just now is you shouldn't travel unless you have a very good reason to do so."
Joanne Dooey, president of the Scottish Passenger Agents' Association, said the travel sector was "wholly supportive" of measures to protect public health.
"There were few travel corridors left open for UK travellers, so we've been moving towards this state for some time now," she said.
"The vitally important step that needs to be taken now is for the UK and Scottish governments to work with our industry to develop a robust strategy for the restarting of travel to and from the UK."
The number of confirmed cases rose by 2,160 in Scotland on Friday, but Prof Leitch said the figure in part reflected the high number of tests carried out in recent days, and possibly "bulk reporting" by care homes.
The proportion of tests coming back positive stood at 7.5%, the lowest figure since Christmas Day.
Prof Leitch said there may be some "green shoots" in the declining positivity figure - but sounded a note of caution.
"If we look at the seven day average, we are a little bit down on the previous seven days so that's encouraging. But it's deceleration, it isn't really turning the corner yet," he said.