Berlin - Germany's main railways company reached a deal with manufacturers Monday to replace 1,200 axles on high-speed trains after a discovery that cracks can develop in existing axles on ICE-3 passenger cars.

Only one axle has ever broken in service: as an ICE-3 train was moving at walking speed out of Cologne station one year ago. No one was hurt. But frequent safety checks disrupted Germany's fleet of bullet trains for months.

The company, Deutsche Bahn, said it had agreed with rolling stock manufacturers Siemens and Bombardier that they would design new, more robust axles, which will require testing and certification by rail safety authorities.

No date was set for the existing axles to be unbolted from the cars and replaced. Till then, ultrasonic checks to detect metal fatigue in the existing axles will take place five to ten times more often than used to happen when the trains first entered service.

Deutsche Bahn blamed the July 9, 2008 accident and cracks found in other axles on inadequate manufacturing procedures.

The electric-powered ICE-3 trains cruise at more than 200 kilometres per hour between main cities. They have no separate locomotive, but deliver power via electric motors to most of the wheels. (dpa)