SNP ministers have been accused of “fiddling” targets for ScotRail after it emerged the rail operator was allowed to miss its contractual customer satisfaction goals two years running.

Research by the Scottish Parliament confirmed the satisfaction targets were lowered in both 2016/17 and 2017/18 on the grounds of unforeseen events.

This meant ScotRail was able to avoid triggering an “event of default”, and the potential loss of its contract, even though it missed its original contractual target in both years.

The Scottish Government last week issued ScotRail with a “remedial plan notice” after it missed its latest satisfaction target because of delays and cancellations.

It followed ScotRail hitting a 16-year low last autumn, with overall satisfaction in rail services at 79 per cent in the first six months of the year.

The contractual target is 88.5% satisfaction in the National Rail Passenger Survey (NRPS),

If it fails to improve, franchise holder Abellio could ultimately be stripped of its contract.

Now it has emerged the satisfaction target was twice changed in ScotRail’s favour.

In 2016/17, the average target was cut to 84%, and ScotRail got 86.5%.

The following year it was cut to 85%, and ScotRail got 85.5%.

The changes have let ScotRail avoid the loss of the franchise which could otherwise be triggered by missing the target in two consecutive years.

Holyrood experts said the 10-year franchise agreement which began in 2015 allows for reasonable changes, and in 2016/17 there was increased disruption caused by Network Rail electrification works and around Glasgow Queen Street, plus a change to NRPS methods.

“The scale of the disruption was not known to bidders when they were submitting bids for the contact,” the research said.

In 2017/18, the target was adjusted downwards again because changes to the NRPS were deemed to have potentially lowered the scores.

“The decision to vary the targets in the previous two franchise years was consistent with the provisions contained in the franchise agreement, which holds constant the risk to ScotRail, but accounts for specific issues not in the train operator’s direct control,” the research said.

However Scottish Labour said ministers had effectively given ScotRail a “licence to fail”.

Transport spokesman Colin Smyth

said: “Whilst passengers stood on platforms for trains that never came, SNP ministers were secretly cutting deals to allow the firm to fail commuters across the country.

“Instead of hauling these chancers in and demanding they deliver what they are paid to do so by the taxpayer, the SNP government let them off the hook. Instead of moving the goalposts for a failing franchise, Scottish Labour will bring our railways into public ownership to give our country a transport system that delivers for the many.”

Quango Transport Scotland, which oversees the rail franchise, said: “Performance has not been where it should be and any agreed remedial plans must bring swift change to reach the levels passengers expect and deserve.

“While we can and do hold the franchisee to account for matters within their control, it is only reasonable we also take account of impacts over which any operator would have no influence.

"Suggestions that we should do otherwise are short sighted, as is the notion we can simply rip up contract given that current reserved legislation requires us to run a competitive tender exercise for any new operator. This would come at significant cost to the public purse and bring upheaval to staff up and down the country.”

A ScotRail spokesperson said: "We run more than 2,400 services every single weekday, which is more than ever before, and our punctuality has recently reached its highest level since September last year.

"But we know there is much more to do, given the challenges we have faced in recent months. Everyone at Scotland’s Railway is working flat out to deliver the service our customers expect and deserve. We will submit a remedial plan to Transport Scotland within the timescale outlined."