400 gallons of fuel leaked from one train

Almost immediately, a Midland Mainline service travelling towards London also struck the metal bar, this time damaging a fuel pipe.

An hour later, at 1615 GMT, a Central Trains service had windows smashed when bricks were thrown, at Wollaton Vale, Nottingham.

Vandals then attacked a second Central Trains unit in the Carlton area of Nottingham, again smashing the driver's windscreen.

British Transport Police and Railtrack have launched a joint investigation into the incidents.

'Disgraceful'

Chief Inspector Colin Edwards of the British Transport Police said: "This kind of behaviour is disgraceful and dangerous.

"In all of these incidents, these people have intentionally tried to harm others and we're extremely lucky that no one has been seriously injured or even killed."

Railtrack Midlands Zone Director Richard Fearn said: "These offenders are lucky that they haven't been killed themselves, but even more disturbing is the injury that could have been inflicted on others."

Railtrack has offered a �1,000 reward for information leading to the arrest and conviction of offenders and Central Trains maintenance contractor Maintrain has also put forward �1,000 to help catch those responsible for the Nottingham attacks.