ScotRail has apologised after a broken down train brought the network in the central belt to a standstill.

The rail operator said it was "the worst type of train failure, in the worst part of our network at the worst possible time".

A train's brakes locked at a main junction near Princes Street Gardens just after 7am on Thursday.

The fault meant the train could not be restarted or moved. Engineers had to split the train into two parts before it could be moved.

The breakdown resulted in all trains in and out of Edinburgh being cancelled for much of the morning, with the disruption carrying on into the afternoon.

ScotRail said it has launched an internal review into the way the incident was handled after it was heavily criticised for a lack of communication.

Phil Verster, managing director of the ScotRail Alliance, said: "I want to apologise for the disruption our customers experienced today.

"The breakdown this morning was the worst type of train failure, in the worst part of our network at the worst possible time.

"We worked hard to get information to our customers as quickly as possible - through social media, our website and app and at our stations."

He added: "While a huge amount of effort went into this, it is clear that some areas worked better than others.

"I know that what people want when disruption happens is to have access to good quality information.

"That is why we will be having a thorough review of this incident to see what worked and what didn't and, crucially, to understand what we need to change or do differently.

"In all my many years working in the railway, this was as disruptive an incident as I have seen. We will do everything we can to learn from it."