Scotrail has pledged to continue working to introduce late night services between Elgin and Inverness.
Concerns were raised when the latest timetable introduced on the line in December did not include the promised improvements.
However, the extra services are dependent on other trains being redeployed from elsewhere in the country.
The last train from Inverness to Elgin currently departs shortly after 9.30pm Monday-Saturday, and at about 9.45pm on Sundays.
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It is understood that delays introducing new electric trains and refurbished Inter7City High Speed Trains in other parts have had knock-on effects between Elgin and Inverness.
Nine extra services on the line have already been introduced but yesterday Scotrail declined to comment on when the late night connections would start.
Work has already begun to make improvements in Elgin to allow trains to remain overnight in the town, which is part of the project.
Moray MP Douglas Ross had received complaints from resident that the last train from Inverness was too early for them to enjoy events in the Highland capital.
He said: “Scotrail has told me that once they have their new fleet of electric trains fully introduced then the existing fleet of diesel trains can be allocated to other routes, including between Inverness and Elgin.
“If this is successful it will allow a later service to be operated from Inverness to Elgin which will allow people to enjoy evening performances at the theatre or other events and then get home by train.
“Although there is no indication when later trains might start running, the plans being put in place are certainly on the right track.”
A Scotrail spokesman said the planned improvements between Elgin and Inverness were just one benefit passengers would see in the coming years.
He added: “We want to encourage as many people as possible to travel by train and to make their journey a seamless one.
“The investment Scotrail and Network Rail are making to modernise the railway – in smart ticketing, new ticketing machines, station improvements, in upgraded trains – means it’s an exciting time for this part of the country.”