Norwegian Air Shuttle said Monday four of its subsidiaries in Denmark and Sweden have filed for bankruptcy, affecting some 4,700 pilots and crew, as a result of the coronavirus pandemic.

The bankruptcies affect 1,571 pilots and 3,134 cabin crew hired locally.

"The impact the coronavirus has had on the airline industry is unprecedented," Jacob Schram, chief executive of Norwegian Air, said in a statement.

"It is heartbreaking that our Swedish and Danish pilot and cabin crew subsidiaries now are forced to file for bankruptcy, and I'm truly sorry for the consequences this will have for our colleagues," Schram said.

Norwegian said there were efficient "furlough opportunities" in Norway where the government covered salary costs, but lamented that there was not "equivalent coverage in Sweden or Denmark".

Another 700 or so pilots and 1,300 cabin crew based in Norway, France and Italy would not be affected, according to the airline.

Norwegian, like the rest of the airline industry, has been hit hard by the drop in demand due to the coronavirus pandemic, coming on top of its struggles with massive debt even before the outbreak.

The company, one of the pioneers of low-cost long-haul flights, is facing cashflow problems as most of its aircraft are now grounded.