Part of the two-carriage service was derailed in the incident

Part of the two-carriage First Great Western service from Swindon to Cheltenham Spa came off the track at Kemble station on Monday night.

The 26 passengers on board had to be helped back to the platform, but none of them was injured.

The line between Cheltenham and Swindon has been closed and a bus service is operating between the stations.

Heavy rainfall

A spokesman for the rail operator said the derailment happened on the approach to Kemble tunnel at about 2200 GMT.

Part of the front carriage ploughed through the landslip and ended up in the tunnel entrance.

The rear coach remained on the line.

An onsite investigation began at first light on Tuesday and an early assessment is that it may take till the end of the week to shore up the bank.

The recent heavy rainfall is being blamed for causing the cutting in the run-up to the tunnel to become saturated and unstable, the company spokesman said.