THE country’s troubled railway service is under further pressure over revelations that there has been a 10% rise in complaints.

ScotRail, which runs the national network, confirmed the jump and promised to “investigate and resolve” the increased levels of dissatisfaction.

The ScotRail Alliance is a partnership between a Dutch private company, Abellio, and state-owned track operator Network Rail.

However, the service has come in for sharp criticism in the last twelve months after failing to meet targets on punctuality and overcrowding.

It was also revealed that trains were deliberately missing scheduled stops in a bid to hit targets, a practice known as 'skip-stopping'.

Phil Verster, who took the flak last year as ScotRail Abellio managing director, quit his post at the height of the controversy over performance.

Figures obtained by the Sunday Herald reveal that complaints about the service increased in the period between January 8 and February 4 this year.

ScotRail has a “key performance indicator” for the number of complaints for every 100,000 journeys. The figure has risen from 29.1 complaints to 32.1 complaints - a 10 per cent rise.

Complaints can be tabled on everything from quality of service to ticketing and punctuality.

Over 20,000 people have now signed on online petition calling on Transport Minister Humza Yousaf to either make ScotRail improve the service or strip the company of its contract. Yousaf has floated the idea of taking the railways into public ownership.

Abellio was awarded the franchise in 2015 for 10 years, but ministers have the power to strip the firm of the contract if punctuality falls below 84.3% for three months in a row.

Scottish Conservative transport spokesman Liam Kerr said: "Humza Yousaf might like to pretend things are getting better on Scotland's railways. But the reality is the opposite, and these complaints and statistics prove that. The SNP needs to sort this out - for too long commuters have been paying too much for a service which frankly isn't good enough."

Labour MSP Neil Bibby said: "Passengers in Scotland are paying over the odds for overcrowded, late running trains, so it's no surprise the number of complaints ScotRail receives has increased.

“After the ScotRail shambles, passenger satisfaction sunk to a 14-year low. Humza Yousaf has to restore confidence in ScotRail and it looks like he’s got his work cut out for him.”

A ScotRail Alliance spokesperson said: “Complaints are up slightly this period and we’re working hard to investigate and resolve them. Depending on when a complaint is received it may be recorded in one period but not closed until the next one. That can see levels fluctuate between reporting periods and the result for this period is within the normal parameters.”

A Transport Scotland spokesperson said: “This KPI measures the number of complaints received made per 100,000 journeys. While we acknowledge the slight increase from 29 complaints in period 11 to 32.1 the next, overall this represents just 0.03% of every 100,000 journeys made.

“Further to this, ScotRail has been working hard to improve performance and the annual average PPM measure is now at 90.3%. We expect this improving performance picture will lead to even fewer complaints being lodged.”