Theresa May said high speed rail was crucial to Britain's prosperity, and that it would solve capacity issues on the over-stretched West Coast mainline.
HS2, which is set to carve through around 45 miles of Staffordshire countryside, has come under fire for spiralling costs, its potential impact on the environment and its impact on areas it passes through.
Mrs May was forced to defend the project after it came under attack from Tory MP Dame Cheryl Gillian during Prime Minister's Questions.
Dame Gillian said: "We are wasting money on a deeply unpopular project, where the management has failed, the costs are out of control and that will end up costing the taxpayer more than £100 billion.
"That's about £300 million per mile of track. Why can't we face up to reality and cancel HS2 and spend the money on the people's priorities for transport, rather than on this over-priced project which will never deliver value for money for the taxpayer?"
In response the Prime Minister said: "We recognise the concerns that people have about their roads, particularly about issue like potholes, which is precisely why the Chancellor has made more money available to address those issues.
"HS2 is not just about a high speed railway, it's actually about ensuring we have the capacity that is needed on this particular route, because we're already reaching capacity on the West Coast mainline.
"We're already seeing HS2 spreading prosperity. It's encouraging investment, it's rebalancing our economy, and that's 10 years before the railway even opens.
"We have seen 7,000 jobs created across the UK and 2,000 businesses across the UK delivering HS2. It will bring tens of millions of pounds worth of benefits to passengers, suppliers and to local communities up and down the route."
Phase one of HS2 linking London to Birmingham is due to open by 2026, with phase two connecting Birmingham and Crewe opening in 2027.
Sir Bill Cash, the Conservative MP for Stone has called the project "a dying white elephant" and has called for a full Government review into it.