Mindless vandals who could have caused a major railway disaster by pushing a large industrial wheelie bin onto a busy line are being hunted by police.

The bin, which had been thrust onto the tracks near Trowbridge this morning, was struck by an early morning freight train and became lodged under its wheels, damaging the braking system.

Had the freight train not been using the line, the heavy metal object would have been clattered by a morning passenger train from Westbury to Cardiff, potentially causing a derailment, transport police said.

Thousands of angry commuters including those travelling either to or from Bath, Bristol and Salisbury were inconvenienced by cancelled or delayed peak-time services following this morning's incident.

As British Transport police launched an investigation, exasperated rail companies branded the culprits as "really stupid" and warned their actions could have had "dire consequences", causing injury or even death.

The wheelie bin was understood to have been hauled onto the line near Trowbridge station during the early hours of this morning before it collided with the heavy freight train travelling from Westbury at 5.28am.

Network Rail spokeswoman Mavis Choong said the bin became wedged beneath the train, damaging its brakes and forcing it to stop.

She said: "The freight train stopped on the tracks and several passenger services had to be cancelled. We are now working with British Transport Police who are investigating the incident.

"We don't yet know how the wheelie bin got there. That will be part of the investigation.

"But potentially this could have been a very serious incident. It could have had dire consequences."

Engineers had to dislodge the crushed bin from underneath the train, check that the railway tracks had not been damaged and remove the crippled vehicle from the line.

Services between Westbury and Bath Spa via Trowbridge were disrupted for three-and-a-half hours, causing misery and frustration for commuters trying to get to work.

Operator First Great Western (FGW) was forced to cancel six services while 16 others were delayed. South West Trains also had to cancel the 6.40am between Bristol Temple Meads and Salisbury.

FGW spokesman Adrian Booth said: "We don't know what exactly would have happened had a passenger train hit the wheelie bin.

"But potentially, this was a very dangerous incident. Pushing an object like this onto a railway track was a really stupid thing to have done."

"CCTV footage is being examined by investigators. We would urge anyone who has any information on this to contact the police as a matter of urgency."

Mr Booth said FGW had to lay on buses to ferry rail commuters to Bath, which added to their frustration as the roads were busy. "That's why they decide to go by train in the first place," he said.

The track was opened again at 9.20am, following repairs to the freight train and the line being checked.

Anyone with information is urged to contact British Transport Police on 0800 405 040.