THE performance of train services deteriorated in the month after ScotRail presented ministers with an "improvement plan".

Labour said it had benchmark figures which showed in the four weeks to September 17, the firm had 90.8 per cent, against a target of 92.5 per cent, arrived within five minutes of their due time.

Over the same period a third of all routes in Scotland had services which were late more often than they were on time.

Read more: Airport expansion in south east England will be a "boon for Scotland," insists David Mundell

Some 90.2 per cent arrived inside the allotted time in the last four weeks.

An improvement plan from ScotRail was submitted to ministers on September 16, and a summary published this week.

Neil Bibby MSP, Scottish Labour’s transport spokesman, said: “Passengers are fed up with the shoddy service they are receiving from ScotRail, which led to an improvement plan being submitted in September.

“Commuters will be aghast to discover that hundreds more trains have been late and performance has actually got worse in the four weeks since that improvement plan was presented.

“We already know that a third of all routes in Scotland have services which are late more often than they are on time, and now the crisis has deepened.

Read more: Airport expansion in south east England will be a "boon for Scotland," insists David Mundell

“With winter fast approaching, passengers deserve a guarantee about when exactly they will see improvements to the punctuality and reliability of services."

A Transport Scotland spokesman said: "As has been well-documented in Parliament and elsewhere, the PIP (improvement plan) was requested by Transport Scotland in August, a first draft was received in mid-September, and since then we have worked closely with ScotRail to ensure the plan was fit for purpose.

"The plan was published by ScotRail on Thursday and included an opportunity for the media to question senior management.

“ScotRail now have a very clear plan going forward and have committed extra funding of up to £16 million and additional resources into meeting these tough performance targets.

"We are confident they can get performance back to a level that meets our challenging contract targets, although we accept it won’t be easy.”

Read more: Airport expansion in south east England will be a "boon for Scotland," insists David Mundell

It comes after passengers were warned to prepare weeks of disruption as engineering works across the Central Belt lead to more trains being cancelled, less frequent, diverted or replaced by buses for all or part of the route.