The additional rolling stock will be among a range of improvements unveiled by the Government as it seeks to deflect criticism it has faced from passengers over the conditions in which they are expected to travel.

Miss Kelly is also expected to announce plans for the next generation of 180mph trains on the inter-city network.

The new generation of trains will be "lean and green", with a lower carbon footprint than the diesel and electric stock they will replace.

Miss Kelly's decision to increase by nearly a third the amount of extra capacity announced by her predecessor reflects the increasing Government concern over the industry's ability to cope with soaring demand for rail travel.

According to industry and Whitehall sources the strategy unveiled by Miss Kelly will focus on "capacity, carbon and customers", with rail being earmarked as a key plank in the Government's drive to increase the use of public transport at the expense of the private car.

The White Paper, which will be introduced to MPs by Miss Kelly, is in reality three documents: short-term plans covering the period up to 2014, the money which will be made available to pay for the schemes and a longer-term vision for the industry over the next 30 years.

But it is the short-term plans which will attract the most attention especially given increasing public discontent over cramped carriages on crowded commuter lines into London as well as in the West Country, where some angry passengers withheld their fares in protest.

Earlier this year, Bill Emery, the head of the Office of Rail Regulation, courted controversy when he called on the Government to use "congestion pricing" to discourage passengers from travelling at peak times.

Within weeks, Douglas Alexander, then Transport Secretary, tried to take the heat out of the controversy when he announced plans for 1,000 more carriages earlier this year. But even this is now seen as being inadequate to meet the growing demand.

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Ministers give green light to rail expansion

Financial Times: July 23 2007
By Christopher Adams, Political Correspondent

Plans to create extra capacity on Britain’s overcrowded railways, including 1,300 new carriages, will be at the heart of an official review to be unveiled on Tuesday.

Longer trains and platforms, fresh spending on signalling and big station upgrades at Birmingham and Reading are expected to be proposed as part of government efforts to ease the pain for long-suffering commuters and to cut journey times.

Infrastructure seen as essential for economic expansion, including a long-delayed extension to London’s Thameslink, will be given the green light. There will, however, be no firm commitment by the Department for Transport to a new, high-speed London-Scotland rail link.

The Financial Times understands that ministers are far from convinced that the billions of pounds needed to finance the north-south project would be well spent. There is concern, too, about the environmental impact of such a scheme.

In a statement to MPs on Tuesday, Ruth Kelly, the transport secretary, will set out the government’s spending priorities for the rail network for the five years from 2009 to 2014.

The announcement will be accompanied by a white paper on the future of rail over the next 30 years. It is expected to focus on expanding the network’s capacity. Some £3bn-£4bn could be available annually for Network Rail to operate the railway – less than is currently available, but still a high level historically.

The government – influenced by the findings of Sir Rod Eddington, the former British Airways chief whose report on the UK’s transport needs was published in December – is likely to place emphasis on improving the performance of existing network assets.

With public spending tight, ministers are anxious to avoid repeating ambitious promises made in the past.

While cool on the “grand projets” that have underpinned railway development in other large economies, there will be explicit support for Thameslink 2000 – an extension to the cross-London link that should improve capacity in time for the 2012 Olympics.

Crossrail, the proposed east-west London rail route, is unlikely to form part of the announcement, however. Its financing is being negotiated between the Department for Transport and the private sector. The Treasury is seeking a substantial contribution from the business community to the cost of this project.

Planned upgrades to Birmingham New Street and Reading will be among practical measures to ease commuter crowding. Proposals for 1,000 extra carriages were set out earlier this year and approval for the Thameslink extension will add to those.

With trains more reliable and safety no longer as big a public concern as it was in the wake of the Potters Bar crash in 2002, overcrowding has become the most pressing concern for ministers. The railways have experienced huge growth over the past decade, and the strong economy in London and the south has put further strain on the network.

Steps to simplify what critics have described as an overly complex fare structure for passengers may also be outlined on Tuesday.