ScotRail has been instructed by the Scottish Government to submit a plan for how it will address falling performance levels.
The rail operator introduced a new timetable earlier this month, which was expected to improve the service.
However passengers faced a number of cancellations across the country with staff training and infrastructure problems leading to significant disruption.
A remedial notice was issued on Monday, citing cancellations throughout November and December as having breached required performance targets.
The notice also applies pre-emptively in relation to ScotRail’s overall performance, as measured by the Public Performance Measure (PPM), with ministers expecting ScotRail to fall below the the PPM benchmark.
A response to the notice must be delivered within eight weeks, outlining how ScotRail will resolve the issues stated.
“This month should have been a celebration of the biggest increase in services and capacity, enabled by our ambitious electrification programme. Instead, we are taking this contractual step of issuing a remedial plan notice.
“ScotRail recognises the reasons for this notice and the importance in returning performance across our rail network to contractually acceptable levels. Passengers want and deserve a railway which delivers the benefits of more seats and services on a consistently reliable basis.”
Alex Hynes, managing director of the ScotRail Alliance, added: “We know that the service our customers have received hasn’t been good enough recently.
“Everybody at the ScotRail Alliance is working flat out to deliver the improvements our customers expect and deserve. ScotRail will submit a remedial plan to Transport Scotland within the eight weektimescale outlined.”