The leap in profits comes alongside criticism that the company is not investing enough money in improving the country's railways and has angered rail passenger lobby groups.

Railtrack's earnings have risen sharply

Although Railtrack has promised to invest £17bn in a 10 year investment programme, the company is reported to have put parts of its plan on hold while it assesses its progress so far.

Railtrack insisted that its plans to upgrade the railway system are on track.

Chairman Sir Robert Horton said: "We have made good headway on our £17bn 10 year investment programme, investing £689m in the first half, and we are on target to spend £1452m by the end of the financial year."

Under fire

But pressure group Save Our Railways said the company's "relentless drive for profits" was hurting passengers.

And the London Regional Passengers Committee (LRPC) said Railtrack's investment programme should be proceeding at a faster pace.

Keith Bill, national secretary of Save Our Railways, said: "Railtrack has slowed up its investment and maintenance programme. Railtrack must learn that it has a duty to passengers as well as to its shareholders, or the government will have step in and teach it that lesson."

LRPC director Rufus Barnes said: "Railtrack was very slow in getting its regeneration programme up and running, with the result that passengers have suffered and, in some cases, are continuing to suffer from rundown stations and equipment."

Transport minister John Reid said: "The government recognises that Railtrack is a private company and must make a profit. Equally it benefits from a substantial public subsidy. We need to be sure that the tax payer is getting proper value for money."

Escalating earnings

Railtrack's profits surpassed City expectations.

Its pre-tax profit for the six months to 30 September increased from £199m to £224m.

Railtrack also claimed that it had slashed the number of minutes trains were delayed due to faulty tracks and signals.

Shareholders, meanwhile, will receive an improved dividend of 8.7p per share, a rise of almost 10%.

Profits were boosted by sales of its extensive property portfolio.

Railtrack said it would continue to look to sell large parts of its property portfolio.

The company said the Channel Tunnel Rail Link, connecting London to Folkestone would provide an enormous growth opportunity, and had the potential to create significant revenues.