A £90 million new train fleet could sit gathering dust because of a bitter row between drivers and the region’s biggest operator.

A total of 27 new diesel locomotives were due to start running on the Snow Hill lines between Birmingham, Solihull and the Black Country within weeks.

But no drivers at London Midland have yet been taught to drive the new engines because they are refusing to work rest days to cover training courses.

Unions leaders at Aslef said there was also a “fundamental disagreement” about the length of time drivers needed to familiarise themselves with the new Class 172s because of its unique braking system.

“These trains are supposed to be coming into service this spring but it’s quite possible that they won’t,” said Aslef official Mick Whelan.

“They haven’t come forward with a training programme and we don’t know how they are going to facilitate that in time.

“They want a far shorter training course than we feel is sufficient.

“They are talking about two or three days and we are talking about 10.”

London Midland is at odds with drivers over Sunday overtime payments being slashed from £400 to £300 and harmonisation on contracts from drivers who were recruited from two different franchises three-and-a-half years ago.

Sunday services have all but ground to a halt in recent weeks and a handful weekday trains have been cancelled because some drivers say they will no longer work on rest days.

London Midland are trying to avert a fresh collision over driver training for the Class 172s and said it did not believe there would be any “undue” delay.

The firm has ordered 15 new three-carriage trains and 12 two-carriage trains to operate on routes out of Snow Hill and Moor Street stations.

On top of the investment in trains, a further £1 million was ploughed in to a state-of-the-art train simulator to help drivers get to grips with the Class 172s.

“The first trains in the £90 million fleet are currently being tested at Tyseley depot in Birmingham, so we do not anticipate training arrangements unduly delaying their introduction into service,” said a London Midland spokesman.

“We are currently negotiating training arrangements with Aslef and are working to reach agreement on a realistic and affordable training schedule with Aslef.”