The row centres on the introduction of new Avantix machines that can issue tickets for travel all over the country and contain detailed train information.

The RMT said staff were being forced to use them without receiving extra money.

The rail firm operates services from Hull, Newcastle, Leeds, York and Sheffield, to Manchester and Liverpool.

'Open to discussion'

The new machines are in operation at most TransPennine locations and other train companies, including Virgin and Midlands Mainline, are already using them.

But, an RMT spokesman said the other companies had agreed a "particular amount of money for training and usage".

About 120 RMT members are being balloted and a result is expected next week.

"We are open to discussions with the company if the result is for strike action," said the spokesman.