A transport union leader today promised to "stop the Government in their tracks" if train fares rose and rail investment was cut.
In a Financial Times interview today, Transport Secretary Philip Hammond warned that the current formula for calculating the annual rail fare increase might be scrapped.
This could mean fares rising by even more than the January 2011 expected figure of about 6%.
Mr Hammond is also looking closely at a number of rail projects in the light of severe cross-departmental cutbacks.
Bob Crow, general secretary of the RMT union, said today: "It could not be clearer. The Government are planning to bleed rail passengers dry and attack essential modernisation programmes while ring-fencing the profits of the train operators.
"That's not sharing the pain. It's locking in the expensive failures of privatisation while hammering the passengers and rail staff into the ground."
He went on: "We could see fares jacked up by as much as 10% while passengers are crammed into ancient carriages running on creaking track with huge safety risks the length and breadth of the country.
"At RMT's annual meeting this week (in Aberdeen) we will be planning the fightback and a mobilisation of rail workers and rail users that will stop the Government in their tracks."