Rail bosses still aim to cut journey times on the flagship Edinburgh to Glasgow service to 42 minutes by the end of next year, despite previous delays and "issues" with the new electric trains.

Transport minister Humza Yousaf said partners involved in the Edinburgh Glasgow Improvement Programme (EGIP) wanted to achieve the target by December 2018.

But he told MSPs that Hitachi, which is producing the new Class 385 trains, was having "some issues" with delivering them, while there had been "well documented" hold-ups in work to electrify the route.

The EGIP project was originally costed at £742 million, with the first electric services expected to come on route in 2016, a deadline that was pushed back until July 2017.

Mr Yousaf said it would now be December before some electric trains are running on the flagship service linking Glasgow Queen Street station and Edinburgh Waverley, with the new Class 385s to be phased in at a later date.

Former Scottish Government transport minister Stewart Stevenson pressed him on the delays when he appeared before MSPs on the Rural Economy and Connectivity Committee.

"We're still aiming towards December 2018 for the 42-minute journey time," Mr Yousaf said.

He told the committee he had spoken to Hitachi bosses at their Newton Aycliffe factory near Darlington, where the trains are being manufactured.

Mr Stevenson said: "My personal sources suggest that Hitachi are having some difficulties with productivity at their plant where the 385s are being built. Are you aware of that or are my sources wrong?"

Mr Yousaf told him: "I was in Newton Aycliffe visiting Hitachi on Monday, I went down to see for myself, as a former transport minister you will know only too well that you will hear different versions from different stakeholders and different sources.

"So I decided to take a look for myself at the 385s and speak to the senior team at Hitachi.

"In fairness to Hitachi they are up front, there have been some issues around the scheduling of their programmes and they are working on a number of projects.

"It's a new plant, it's only a few years old, it is a very impressive plant in terms of the size and the scale of the workforce."

He said Hitachi accepted that they "have had issues around the programme scheduling, therefore delivery".

The minister said: "It is fair to say some of the problems and issues have come on the manufacturing side. But it is also very fair to say there clearly is, as is well documented, there have been delays with the electrification process."

Mr Yousaf added: "What I've said to all partners is, frankly speaking, I will deal with whose fault it is when the time comes. Let's get these trains, the 385s, lets get them built, let's get them tested and let's get them into service and running here in Scotland."

Bill Reeve, director of rail at the Scottish Government, said that testing of the new trains had revealed some "issues".

He told the committee: "There are issues arising on testing, which is what you do testing for, which will require some work to address some of the issues.

"Some of that work will take place in Newton Aycliffe, some of that work will take place in Scotland."

Rail operator ScotRail has ordered 70 of the new trains as it expands its electric railway network, with managing director Alex Hynes having told MSPs earlier this month that he could not guarantee 21 of them would be available when they are due in February.