A £1.1bn rail electrification project on one of the UK's major routes will cut journey times, reduce pollution and boost the economy, the government said yesterday.

A £1.1bn rail electrification project on one of the UK's major routes will cut journey times, reduce pollution and boost the economy, the government said yesterday.

The announcement of the new investment on the Great Western Main Line was the centrepiece of a UK Cabinet visit to Wales that the Prime Minister used to hail a new age of the train.

"It just shows that railways are back and that the investment in railways will pay off for the future," Gordon Brown said.

The plans will transform the Great Western Main Line, which runs from London to Oxford, Newbury, Cardiff and Swansea via Reading.

With the new investment it is expected that journey times from London to Swansea will be reduced by 19 minutes and train capacity in rush hour will increase by 15%. It is also predicted that 25% less carbon will be produced by the new trains.

The electrification of the London to Swansea route will cost £1bn and could take eight years to complete. The government said it would also spend £100m on electrifying the rail network from Liverpool to Manchester over four years.

Mr Brown said: "This is the future. It is green, it is faster and it's more reliable. This is about making the railways fit for the 21st century. We have set aside money for this.

"It's an important priority for us."

The Conservatives questioned where the finance was coming from and the news came as a disappointment to campaigners in the East Midlands, who had supported the electrification of the network from London to Nottingham and Sheffield.

Large parts of the West Coast Main Line and the East Coast Main Line linking Scotland to the rest of the UK are already electrified.

However industry and passenger bodies welcomed the fact that Wales, one of only three nations in Europe without a single mile of electric rail, was getting a transport boost.

"The announcement is excellent news and a clear demonstration of strong government commitment to modern rail transport," said Michael Roberts, chief executive of the Association of Train Operating Companies.

"The electrification schemes will bring real benefits to passengers and the environment."

Network Rail chief executive Iain Coucher said: "Today is a good start, but there is much further to go. We have been pushing for electrification for a long time. Also, further electrification will also help open up more diversionary routes so that we can keep people on trains and off buses as we carry out planned rail improvement work."

Mr Brown said that the eight-year project on the Great Western route from London to Swansea would make the service greener and more reliable and transform it into a "world-class" operation.

Only about one-third of the rail network is electrified at the moment, with the Great Western route the last of the major routes to be still predominantly using diesel trains.

Travelling with Mr Brown, Transport Secretary Lord Adonis said: "We are electrifying 300 miles of track and we are also looking to extend electrification to other lines. There will be some disruptions while the work is going on but Network Rail plan to keep disruption to a minimum, with much of the work being done overnight."

Lord Adonis went on: "Electrification will mean faster, quieter and more efficient trains, which break down far less often."

The announcement follows Network Rail's consultation document on electrification earlier this year, which also made the case for electrifying the Midland route.

Lord Adonis said that the government would continue to consider the East Midland Main Line for electrification.