A Deutsche Bahn spokesman told AFP the companies involved in the lawsuit were "big corporations", but declined to give the exact number or their identities.
The company had announced in December it was filing lawsuits in Germany and the United States claiming compensation for damages it says its subsidiary Schenker sustained as a result of fixing of airline freight prices.
Deutsche Bahn is seeking over €2 billion euros from around 15 airlines, a sum that it said will exceed €2.9 billion once the claims of the other companies are added on.
Brussels and the United States along with Canada and Australia among others have already imposed fines on the air cargo cartel.
In 2010, Europe's competition watchdog hit 11 airlines with nearly €800 million in fines for running a global cargo cartel that included Air France-KLM, British Airways and Japan Airlines.
According to the EU Commission, various airlines colluded in fixing cargo flight prices between December 1999 and February 2006, agreeing kerosene and security surcharges bilaterally or multilaterally.
In the United States, Deutsche Bahn is seeking €300 million from seven airlines including Air France, KLM, Qantas and Scandinavia's SAS.
In Germany, the company is seeking €1.7 billion from ten companies, with Lufthansa, British Airways, Japan Airlines, Latin America's LAN and Singapore Airlines among them.
"We hope that the companies will choose the path of negotiation, that is our goal," a spokesman had said last year.