Rail passengers were trapped inside a tunnel for more than an hour when a London to Rochester train split in two.

The train, which left Victoria station at 5.45pm on Wednesday, split in South London at about 6.20pm.

The first four carriages came to a halt in Penge tunnel, while the final four were left at Sydenham Hill station, some 10 feet behind. The train was carrying around 500 commuters.

People in the rear part of the train were able to get out onto the platform, while those inside the tunnel had to wait an hour and a half while engineers were called to check the units and make arrangements to move all the carriages back into Sydenham Hill station. No-one was hurt in the incident.

All passengers were taken off the train by about 7.45pm and the line reopened 45 minutes later.

Passengers were able to board alternative trains and local buses but many were delayed.

Rail operator Southeastern said the carriages involved in the incident have been taken out of service and transferred to a depot at Slade Green, where a full investigation into what caused the trains to divide is being carried out.

A spokesman said: “While no one was in immediate danger we appreciate this would have been concerning for passengers onboard.

“And it would have been frustrating for many as it meant their journeys home were delayed.

“A safety mechanism means that in the unlikely event of train units dividing in service – and this was a very unusual occurrence - the brakes are automatically activated and an alarm sounds in the driver’s cab.

“Early indications suggest that the fault lies with one of the train’s coupling units.

“Further tests are now being carried out.”