MP, Mark Oaten, denounced moves to allow rail operators to increase train fares by 4% from January 2004 saying it was "unacceptable".

The Government announced last week that the cost of a regulated fare would be allowed to increase by 1% more than the rate of inflation: previously the limit was 1% below that level.

Around 45% of rail fares are regulated. These are non-leisure time fares, capped by the Strategic Rail Authority and include commuter fares at peak time.

The move would mean the cost of an annual return from Winchester to Waterloo, £2,988, could increase to £3,120.

Mr Oaten said: "Commuters are suffering from a train service that is simply not delivering, with almost three out of ten trains are delayed.

"Expecting people to pay 4% more is unacceptable. Services must improve before such price rises can be considered."

Jane Lee, spokesperson for South West Trains said: "It is a fact that the railway needs investment and that can only come from tax or the fare payer.

"Over the past few years, the amount of money from the fare payer has reduced and fares have fallen in real terms."

She said that because of capping, fares had not risen as much as the cost of living. She said a season ticket bought in January, 1995 would have cost £2,732 and in 2003 it was £2,988 - an increase of only £256 in eight years.

Recent figures, however, showed South West Trains had only 65% of trains arriving on time in the first quarter - compared with a national average of 80.5%.

She said year-on-year, South West Trains had had a 20% reduction of train delays, but admitted punctuality was still not good enough.

Mr Oaten said: "Instead of demanding more money from passengers, operators and the Government need to work out a way of spending money more effectively to deliver higher quality services."