Passengers could face a rise in off-peak fares of up to 30% in a major review of rail ticket prices, according to union leaders.
Prices could rise steeply as train companies try to make more money from commuting that happens just outside the rush hour, according to a report in the Metro.
At the moment off-peak travel is considerably cheaper than peak travel with a sharp cut off time of 9:30am in many areas.
The report will be announced later today by transport secretary Philip Hammond after a study was conducted by Sir Roy McNulty.
Mr Hammond is looking to make cuts of £1 billion from the industry's £5.2 billion running costs and the train ticket prices are just one part of that, along with job cuts on trains and in rail offices.
Hammond also wants to simplify the ticket buying system with a price structure similar to airlines, where passengers pay more on busy trains and less on empty trains.
Speaking to The Mirror, Bob Crow, general secretary of the Rail, Maritime and Transport union said: "The Government are clearing the tracks for a massive assault on rail jobs, ticket offices and drivers' pay and conditions."
Reported in the Metro, Gerry Doherty, who works for the Transport Salaried Staffs' Association union, said: 'If inflation stays at about five per cent, passengers are already looking at huge increases of more than 20 per cent over the next three years.
"Now, Sir Roy McNulty wants some off-peak fares to go even higher than that, to ease overcrowding around the peak hours.
'We could easily be looking at a 30 per cent jump in off-peak fares at a time when passengers already pay the highest fares in Europe.'