German rail officials say the workmen are missing, presumed dead. But there are no details yet of the kind of work they were carrying out - nor whether they trying to correct a fault which may have contributed to the crash.

The disclosure came as an official inquiry opened into the train crash.

Investigators have discounted one early explanation for the accident - that the express derailed after hitting a car on the line.

The wreckage of a car was discovered at the scene, but it is now thought that it fell off the bridge as the structure was demolished by the train.

The driver has told investigators that the train had not hit anything before the crash.

The Inter-City Express was travelling from Munich to Hamburg when it derailed near Eschede and collided with a road bridge support. The bridge collapsed, flattening three of the train's 13 carriages.

Train split in two

Another theory being examined by investigators is that the locomotive somehow de-coupled from the rest of the train, which then collided with the bridge.

This has been supported by comments made by the train driver.

"The train engineer felt a tug which automatically released the brakes, and then he looked out the window and noticed he no longer had a train behind him," said investigator Gisela Luening.

German railways official Peter Muenchschwander said: "The train split in two.