The European Commission charged several airlines with price fixing on freight services.
British Airways, Lufthansa, SAS and Air France KLM said they were among those affected.
The European Commission said it had sent official charge sheets, known as statements of objections, to several air freight companies.
"The European Commission can confirm that a statement of objections has been sent to a number of companies, concerning their alleged participation in a cartel in the provision of air freight services, in violation of EU rules on restrictive business practices," the commission said.
Cargo receipts are a reliable stream of revenue for passenger airlines, which carry mail and other freight. In response to higher fuel costs last year, airlines had said they would hike fuel surcharges on freight shipments.