BERLIN -- The organization in charge of Berlin's commuter rail service is suing Bombardier Transport (TSX:BBD.B) for $468 million over allegedly defective trains.

Deutsche Bahn¡ is suing the German-based Bombardier subsidiary in regional court because of what it describes as serious defects.

The rail operator says the wheels and axle-shafts on trains have had to be redesigned and replaced at great financial cost.

Braking systems and traction motors have also been adapted and, in some cases, replaced.

"Over the last few months, DB had attempted in vain to reach an agreement in the form of an out-of-court settlement," said a statement Monday.

"On expiry of the standstill period, the company has now decided to have the matter clarified by the court and is suing Bombardier."

There are separate suits pending against Bombardier in Munich and Berlin regional courts, related to other trains, with Deutsche Bahn seeking another $214 million in compensation.

In response, Bombardier issued a news release disputing the allegation Monday. It said it could even take steps to counter what it described as "defamatory" statements.

It said that the Deutsche Bahn subsidiary, S-Bahn Berlin, had always been responsible for any maintenance work required on those trains.

"Bombardier Transport is not subject to any contractual commitment related to the maintenance and repairs on the 481 series," said the statement.