A German man has been arrested on suspicion of having loosened the bolts on a high-speed train track between Cologne and Frankfurt.



The man, described by Frankfurt’s state prosecutor as being “without fixed abode”, was arrested near Cologne on Friday night after police found specialist equipment for loosening track bolts in his car.



Investigators reportedly tracked down the 51-year-old after a confession letter referring to the location of the attempted sabotage was sent to several politicians, including the chancellor, Angela Merkel.



According to Der Spiegel, the suspect was only recently released from prison in Nuremberg, where he had served a sentence for attempted blackmail.



German police had reported a “possible attack attempt” earlier on Friday after the driver of a high-speed Intercity Express train noticed something unusual in the early hours while crossing Theisstalbrücke bridge near Niedernhausen, just outside Frankfurt.



Several trains had already passed over the damaged track before the tampering was uncovered, police said. If the loosened rails had not been reported early, one of the trains could have derailed off the 50m-high bridge, German media reported, citing investigators.



The general prosecutor in Frankfurt would not comment on a motive for the attempted attack while investigations were ongoing.