It happened on a Central Trains route from Nottingham to Skegness at about 1900 GMT on Monday as the train passed the Colwick level crossing.

Police have been called to the same stretch of railway line 35 times this year.

The track, through Colwick and Netherfield, has been plagued by trespassers and vandals.

'Serious implications'

One passenger on Monday night's train told BBC Radio Nottingham the train tipped on to one side and was plunged into pitch darkness.

Other witnesses described hearing a loud bang as the delayed commuter train crashed into the slab and power was cut.

Sergeant Mark Clements from British Transport Police said: "They could easily have been hit by a passing train and result in death.

"It does have very serious implications for safety of the railways."

So far this year the police have dealt with an average of almost one incident a week on the same piece of track.

Three trains hit obstacles which were placed on the line.

Others have had their windows smashed by missiles such as bricks and one was shot at with an air gun.