ScotRail has blamed a shortage of older diesel trains for delays rolling out promised improvements to the Aberdeen to Inverness line.
A £300million improvement project financed by the Scottish Government and run by Network Rail is currently under way on the line.
Work was completed on the Inverness to Keith section two years ago while engineers are currently working between Huntly and Dyce to lay more track to increase capacity.
However, promised improvements, including a later last train from Inverness to Elgin, are yet to materialise due to a shortage of rolling stock.
Moray MSP Richard Lochhead met ScotRail’s managing director Alex Hynes last week about fears that the level of service is not matching the investment.
He said: “I conveyed the real frustrations rail users in Moray have, particularly around overcrowding and there not being enough carriages put on for busy services.
“Mr Hynes explained that one of the key challenges ScotRail faces is the lack of available diesel trains across the UK – which seems to be a legacy issue from when the previous Labour UK Government made a move away from them without consideration for areas where we don’t have the infrastructure to support electric trains.
“However, the fact is that the number of people using the Aberdeen to Inverness line is increasing so we need ScotRail to respond to that by delivering on its plan to increase its rolling stock so there are enough seats for passengers.”
Improvements promised to the service on the line include half-hourly connections between Aberdeen and Inverurie with more during peak times, new early morning and late evening services between the Granite City and Elgin and more direct links from Aberdeenshire and Moray to Edinburgh and Glasgow.
An hourly service between Inverness and Elgin has already begun while more sections of double-track are expected to increase the reliability of journey times.
A ScotRail spokesman said: “The successful delivery of our remedial plan remains a priority for everyone at ScotRail and it’s promising to see the progress we have made in such a short period of time.
“But we know there is more to do. The work we are doing now will mean more seats, faster journeys and better services for our customers.”