Air France-KLM passenger numbers plunged nearly 57 percent in March and it expects more than 90 percent of its planes to be grounded this month and in May due to the coronavirus crisis, the group said Thursday.

The company said given the restrictions imposed on air travel, it would slash capacity but maintain key routes from its two home hubs -- Amsterdam-Schiphol et Paris-Charles-de-Gaulle.

Air France-KLM, one of the world's largest airline groups, has helped repatriate French and Dutch nationals stranded abroad by the outbreak.

It said it could not provide any guidance on its business beyond May due to the uncertainties caused by the coronavirus spread.

By sector in March, Asian region passenger traffic was down 65.7 percent compared with a year earlier, with North America falling 48.9 percent, Africa-Middle East 40 percent, Carribean-Indian Ocean 38.3 percent and Latin America 37.8 percent.

The group added that it was suspending its monthly traffic reports until further notice.

Airline industry group IATA estimates that the coronavirus outbreak will cost its members some $259 billion this year alone.