An investigation has been launched after a Caledonian Sleeper train was forced to make an emergency stop when it overshot its platform at Edinburgh Waverley station.

Staff on the northbound Lowlander service activated the train's emergency brake to bring it to a halt several hundred yards past the platform on Thursday morning.

The train came to a stop across a junction on the line, blocking services to London, Dunbar, North Berwick and Tweedbank, before it was pushed back to the platform.

The Rail Accident Investigation Branch (RAIB) immediately launched a probe into the incident, with inspections of the scene and the train being carried out to determine the cause of the out-of-control vehicle.

A spokesman added: "An RAIB inspector was deployed yesterday to gather evidence.

"We will use this information to decide any further course of action."

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The incident sparked calls from a transport union boss to stop using the newly launched trains, which were introduced from the end of April and have suffered numerous problems and votes for industrial action from staff over working conditions.

Serco, the operator of the Caledonian Sleeper service, apologised for the incident but claimed "early indications are that there are no technical problems with the rolling stock".

Following the incident, the Caledonian Sleeper's Twitter account posted: "Our apologies to guests affected by the incident at Edinburgh this morning.

"Our northbound service to Edinburgh Waverley overran the platform due to an earlier operational issue at Carstairs.

"An investigation is under way into the cause of the incident but early indications are that there are no technical problems with the rolling stock. We have notified the relevant authorities."

TSSA general-secretary Manuel Cortes said: "Clearly this is an incredibly serious situation which calls for nothing less than the grounding of the entire new Sleeper fleet until we have the full details of the what went wrong.

"No-one should be playing fast and loose with faulty brakes on our railways and Serco need to wake up to that fact and act now."