* Follows fine by cartel office in July
* Deutsche Bahn suing Thyssenkrupp, Vossloh, Moravia
* Shares in Thyssenkrupp down 1 pct (Adds further background)
FRANKFURT, Dec 20 (Reuters) - German state rail operator Deutsche Bahn has filed a 550 million-euro ($729 million) claim for damages against a number of track suppliers including ThyssenKrupp, after four companies were fined earlier this year for operating a cartel.
In July the Bundeskartellamt fined four companies - ThyssenKrupp, two units of Voestalpine and Vossloh - a combined 124.5 million euros for price-fixing, and said it was investigating others.
Having said at the time it planned to seek at least 100 million euros in damages from the cartel members Deutsche Bahn said on Thursday it had since tried to reach an out-of-court agreement but some parties had broken off talks.
“And that’s in spite of the fact it has been established without doubt that they caused damage to us. We see no other course but to take legal action,” said Gerd Becht, Deutsche Bahn’s board member for regulatory compliance.
The state-owned company said it was suing ThyssenKrupp, Czech group Moravia Steel, Vossloh and the former owners of a Vossloh unit.
Deutsche Bahn did not give details of the amount it was seeking in damages, but the court in Frankfurt where the claim was filed said it was for 550 million euros.
ThyssenKrupp said in reaction Deutsche Bahn had not mentioned a sum during talks and added that it wished to continue negotiations in January.
Meanwhile Voestalpine, which is not among those being sued and had acted as whistleblower in the case, said it was still in talks with Deutsche Bahn over a settlement.
Vossloh declined to comment.
Shares in ThyssenKrupp were down 1 percent at 18.38 euros at 1016 GMT, one of the biggest fallers on the DAX.
“In the worst case, the potential damage for ThyssenKrupp could range between 300 million and 400 million euros,” said DZ Bank analyst Dirk Schlamp.
As Deutsche Bahn is state-owned, a large part of any damages awarded would go into public coffers, the rail operator said. ($1 = 0.7542 euros) (Reporting by Matthias Inverardi, Victoria Bryan, Angelika Gruber and Tom Kaekenhoff; Editing by Greg Mahlich)