Theresa May has committed to delivering the HS2 high-speed rail link.
The Prime Minister was reportedly coming under pressure from Tory MPs in the south to cancel HS2, which the Government projects will cost £55.7 billion.
But her announcement will end speculation that she was preparing to drop the new north-south railway from the Conservatives' general election manifesto.
In an interview with the Yorkshire Post, Mrs May said: "We remain absolutely committed to HS2.
"It is a very important infrastructure project for the country. It is important that we increase capacity on this mainline and I believe that HS2 is the right way to do that.
"I'm very keen that we do have a country that works for everyone, and that means every part of the country, and that's why we've introduced the modern industrial strategy, we've consulted on that and had very good and positive constructive response from business on that.
"Because we want to ensure that in every part of the country we are identifying the benefits they have, the types of economic development that are best suited. How can we encourage that?
"Infrastructure development is a hugely important part of that, it's why in the Autumn Statement we were clear that we we're putting extra money through to 2020 in infrastructure development."
Phase 1 of HS2 is due to open in December 2026 and will see trains travel at high speed between London and Birmingham before running on from Birmingham on the existing West Coast Main Line.
A second Y-shaped phase will open in two stages. Phase 2a from the West Midlands to Crewe will launch in 2027 and phase 2b, from Crewe to Manchester and from the West Midlands to Leeds, South Yorkshire and the East Midlands, will open in 2033.
Mrs May was more cautious about fully committing to any "HS3" or "northern powerhouse" rail link.
In the 2016 Budget, former chancellor George Osborne set aside £60 million to develop plans to cut journey times to around 30 minutes between Leeds and Manchester, as well as improving transport connections between other cities in the north.
The PM told the newspaper: "The issue is there are a number of options that are being looked at in relation to HS3 or northern powerhouse rail.
"But what I would say is those big projects are not the only way in which we are looking to invest in transport in the region."
She added: "Work is still being done on (northern powerhouse rail) but there are number of options that have been put forward for it."