Transport Secretary Alistair Darling today cleared the way for inflation-busting fare rises on Sussex commuter rail routes.

Rules which kept price rises on key routes pegged to 1% below inflation have been abolished and fares are likely to go up by 4% in the New Year.

Mr Darling's announcement follows a consultation exercise by the Strategic Rail Authority and comes in the same week as official figures revealed rail punctuality was worsening.

Passengers' groups have expressed outrage. Anthony Smith of the Rail Passengers Council said: "This is a bleak day for passengers.

"We have always said that there should be no above-inflation fare rises until performance on the railway has improved.

"They should only come back to the passengers and ask for more money when they have put their own house in order."

But Mr Darling said the rail industry, including the Rail Passengers Council, had agreed that "continuing to peg regulated fares below inflation was simply not sustainable".

He went on: "This was a difficult decision but it's essential to strike the right balance between the contribution from the fare payer and the contribution from the taxpayer."

Also scrapped will be a formula whereby fares on London commuter services could increase and decrease depending on operators' performance.

The Strategic Rail Authority said passengers would, on average, pay an extra £45 a year in real terms for their season tickets by January 2006.

London-Brighton commuters can expect weekly season tickets to go up from £68 to £70.10 by then.

Strategic Rail Authority (SRA) chairman Richard Bowker said: "Fares must keep pace with investment. There is universal agreement that investment is running at record levels; it is wrong for fares to keep falling."

The SRA is also being asked to develop a new national discount railcard.