Swedish, Danish and Norwegian pilot unions earlier this month called a strike if there was no agreement on wages and other terms after an earlier round of talks broke down without the parties finding common ground.

"We are still in negotiations and hoping for a solution but have had to take precautionary measures for those passengers that are travelling early tomorrow morning," SAS spokeswoman Freja Annamatz said.

"This means we have cancelled 205 flights," she said.

National mediators in the three countries have been trying to broker a deal since last week between delegations of the two parties.

As many as seventy thousand travellers could see their flights cancelled on Friday unless negotiators agree a last-minute deal to stop nearly all of SAS' around 1,500 pilots going on strike after midnight, Annamatz said.

The airline normally flies around 800 flights per day.

A strike would affect 70 percent of SAS flights. The remaining 30 percent are operated by partners that would not be affected by strike action, Annamatz said.

Should a strike last through the weekend, around 170,000 travellers would be affected in total, she added.

Earlier this week, the airline offered travellers concerned about a possible strike the chance to reschedule flights for the April 26-29 period to another date free of charge.

SAS is in the midst of renewing an elderly and fuel-intensive fleet after spending years cutting costs in the face of cut-price competition from budget carriers such as Norwegian Air Shuttle and Ryanair.

The airline reported a bigger than expected loss for its fiscal first quarter in February, but said it still expected to run a profit for the full year.

(Reporting by Anna Ringstrom, Jacob Gronholt-Pedersen, Andreas Mortensen, Nerijus Adomaitis and Esha Vaish; Editing by Niklas Pollard and Jan Harvey)