RAIL bosses are facing questions after “troubling” frequent closures of key Scottish train lines.

MSP Kevin Stewart, a former transport minister, wrote to ScotRail after Tuesday saw the Aberdeen to Dundee rail line shut down due to a “defect”.

Trains faced “major disruption” while engineers probed the reported fault, near to the site of the 2020 Stonehaven crash which killed three people.

After the track reopened around 3:20pm, Network Rail, the UK-Government-owned body which manages the rail lines, said that trains from Aberdeen to Dundee were limited to 20mph.

This speed restriction was lifted slightly before 5pm.

Stewart wrote to Network Rail on social media: “Safety is paramount, but the closing of this line is happening far too often.

“What are you doing to ensure that the line can be opened as soon as possible?

“What long term action are you taking to ensure fewer closures in the future?”

The National:

The SNP MSP for Aberdeen Central also penned a letter to Alex Hynes, the managing director of ScotRail, raising similar questions.

Stewart’s letter said: “I am writing to you regarding today's closure of the Aberdeen-Dundee line.

“I am extremely concerned to hear that this line has closed yet again due to a potential track defect. Safety is, of course, the most important thing here. However, I find it quite troubling just how frequently this line has to close due to safety concerns.

“I would be grateful if you could confirm what you are doing to ensure the line reopens as soon as possible. Further, I'd be grateful if you could confirm what long term action you are taking to ensure closures are limited in the future.”

ScotRail said that the issue was for Network Rail to answer.

Network Rail has been asked for comment.