ScotRail's train performance has tumbled and is now below target, figures showed today.
A total of 88.3 per cent of its trains were classed as punctual in the four weeks to 14 October.
That was down six percentage points on the previous four weeks.
It is also nearly two points worse than this time last year.
ScotRail blamed the slump on a series of incidents which caused major disruption.
They included track and overhead line faults, the theft of signalling cable, and another train running through a red light.
Punctuality over the last 12 months also slipped marginally, by 0.1 per cent to 91.1 per cent, which is 0.2 points below target.
This measures the proportion of trains which arrive at their destination within five minutes of time.
Last autumn, after performance dipped below target for three months in a row, ministers agreed to an improvement plan with ScotRail which led to punctuality rising.
ScotRail Alliance infrastructure director David Dickson said: “This has been a challenging few weeks, but we are doing everything we can to address any problems that arise quickly, to take preventative action wherever possible and make sure our customers are given good quality information."
The incidents included overhead line problems at Pollokshields in Glasgow on 19 September, cable theft or damage at Inverkeithing in Fife on 25 September and 4 and 5 October, an empty Caledonian Sleeper locomotive passing a red light in Edinburgh on 30 September, and a points fault in Pollokshields on 10 October.
ScotRail said the locomotive incident led to all signals on that line turning red.
A spokeswoman for the Scottish Government's Transport Scotland agency, which is in charge of the ScotRail franchise, said: "Since the introduction of the performance improvement plan (Pip), ScotRail have demonstrated several consecutive months of improved performance and a record passenger satisfaction rating.
"A dip in performance is seen on many railways across Europe during autumn and ScotRail are not immune to that.
"We are working closely with ScotRail to ensure everything that can be done is being done to maintain previous good progress.
"The Pip remains in place, just as it has done in previous months, to ensure this happens."