"We have today warned 2,500 employees there could be temporary lay-offs. A final decision will be made on Monday," SAS spokeswoman Elisabeth Manzy told AFP late Friday.
Only employees in Norway had received the warning because Norwegian law requires two days of advanced notice in these cases, she said, adding that workers in Sweden and Denmark would be notified later since laws there were different.
"We can't fly. Our entire fleet is on the ground ... There is nothing for them to do," Manzy explained.
All SAS flights in the company's hub cities Copenhagen, Oslo and Stockholm have been cancelled until Saturday at 1500 GMT at the earliest, "but everything could still be closed on Monday," she said.
All employees hit by the temporary lay-off would get their job back once flights were back in the air, Manzy said.
The lay-offs "will last only as long as this extraordinary situation is happening," she said.
SAS cancelled 742 flights on Friday, grounding all but a few flights in the north of Norway, where services restarted at a very slow pace.
The company has refused to say how much the volcano blast had cost it but according to Danish Boarding.dk, a specialised air travel news site, SAS was losing around 120 million Danish kroner ($22 million) per day.
Millions of passengers remained stranded across Europe after a huge cloud of ash from a volcano eruption that began in Iceland on Wednesday swept across Europe, grounding thousands of flights in the biggest air travel shutdown since World War II.