Thousands of rail passengers face fare increases after train companies said they would cut the number of discounted tickets.

Under the plan people who buy the popular Network Card would be unable to get reductions on any off-peak journey costing less than £10.

The card, costing £20, is used by thousands of passengers to obtain a one-third discount on weekday fares after 10am.

An off-peak day return ticket from Brighton to Worthing costs £3.60. With a Network Card the fare is £2.40.

Rail operators said they were losing between £5 and £10 million a year because the cards were encouraging people to travel on cheapertickets.

Passengers' groups, however, condemned the move, saying poorer travellers are being targeted because off-peak fares are not regulated.

Phil Gruber, Sussex spokesman for the pressure group Rail Futures, said: "I think it is dreadful. It is no way to encourage people to use the railways."

Shelley Atlas, of Brighton Line Commuters, said rush-hour trains would become more overcrowded.

She said: "They are not making it very attractive to travel off-peak. They are going to lose money because they will stop people making use of that railcard."

The Association of Train Operating Companies said money being lost because of the scheme, which has beenoperating since 1986, could be reinvested in better services.

There would be no new restrictions on using the cards at weekends or bank holidays and other types of railcard would not be affected.

Train companies are due to meet again in four weeks but if they do not change their minds the new arrangements are to come into force on June 2.