The Government has been accused of "betraying" rail passengers after scrapping plans to electrify three rail lines.
Labour and the Liberal Democrats criticised the announcement by Transport Secretary Chris Grayling setting out plans for new trains on the Midland Main Line, Great Western Main Line and in the Lake District.
The Department for Transport (DfT) said that because of new technology, the electrification works between Cardiff and Swansea, Kettering, Nottingham and Sheffield, and between Windermere and Oxenholme, will no longer be needed.
The DfT said modern "bi-mode" trains which can switch from electric to diesel mid-journey will be used on the Great Western and Midland Main lines, with passengers in Wales benefiting from new Intercity Express trains which will each deliver over 130 more seats and faster services.
Long-distance journey times from Nottingham and Sheffield will be reduced by up to 20 minutes in the peak, with the train operator in the Lake District beginning work to trial an alternative-fuelled train, it said.
Opposition parties seized on the decision not to complete electrification of the routes, saying voters had been 'taken for a ride'.
But the DfT said: "Passengers will benefit sooner and experience less disruption compared with putting up intrusive wires and masts along routes where they are no longer required."
Mr Grayling said: "We are making the biggest investment in the railways since the Victorian era and upgrading services across the country, including in Wales, the Midlands and the North.
"Passengers expect and deserve high quality rail services and we are committed to using the best available technology for each part of the network, delivering significant benefits for those who use our railways."
However, Liberal Democrat transport spokesman Jenny Randerson said: "This decision is a betrayal of passengers across the country who would have benefited from these upgraded routes.
"The Liberal Democrats secured vital investment for rail electrification when in government. That was then delayed by the Tories and now has been scrapped altogether."
Labour's Shadow Transport Secretary Andy McDonald said: "The Tories have been promising the electrification of the Great Western Mainline from Paddington to Swansea since 2012 and today's announcement confirms that they have been taking people for a ride.
"The cancellation of works means passengers will be denied the faster, greener, more reliable train journeys they were promised, and South Wales will miss out on the economic activity that improved rail services delivers.
"The decision betrays a promise to South Wales, and the Transport Secretary sneaking out the news on the final day before he goes on his summer holidays adds insult to injury."
Mick Cash, leader of the Rail, Maritime and Transport union, said: "This Government's talk of rail investment is just jam tomorrow when in reality important upgrade and renewal work across the UK is being shelved and scrapped due to on-going austerity."
Later, Mr McDonald led calls for the Transport Secretary to come to Parliament to defend the "disastrous U-turn", rather than "sneaking" it out on the last day of Parliament so MPs could not challenge the plans.
Raising a point of order in the Commons, he said: "Today, on the last day of the session, a statement has been sneaked out which is of massive economic detriment to the country, and lays waste to any semblance of industrial strategy, and totally conflicts with what was said on Monday night at the despatch box about electrification, and smashes to bits the Government's promises to the people of the North and the Midlands, and especially to the people of South Wales."
Deputy Speaker Eleanor Laing said it was not a matter for her to decide but assured MPs the message would be heard.