NEW trains earmarked for the TransPennine Express lines will be able to seat fewer passengers than now.
Operator First had planned to buy 56 new trains but will now only purchase 51 in the £230m deal.
The fleet will have fewer seats than the older stock it is replacing.
Rail campaigners have hit out at First for reducing the size of order for the trains, which run through Huddersfield.
A First spokesman said the figure of 56 new trains had always been provisional.
But he said the trains - which Siemens is building in Germany - would be timetabled to provide more seats on peak morning services into Manchester and Leeds than are currently available.
Peter Davies, chairman of the Yorkshire branch of pressure group Rail Future, questioned the decision.
He said: "By reducing the order by five trains we are not going to get rid of overcrowding."
He said something had to be done about the chronic crowding on the network.
"Leeds to Manchester is a core section of the route and this is where the extra trains are needed.
"It's such an intense service it's not satisfactory at all. A reduction in the order is not going to help."
He said there had been no noticeable changes to the service since Arriva lost the franchise.
"As far as I can see nothing has really improved," he said.
The TransPennine Express franchise, which First began running in February in conjunction with French group Keolis, links Newcastle and Leeds to Manchester and Liverpool.
It serves 13m passengers.