The cost of completing all three phases of the controversial high-speed rail link was set at £55.7bn, but new sums suggest this could now rise to more than £106bn.
Add this to the estimated costs of transport infrastructure connections to HS2 terminals and the cost of rolling stock and power requirements – the project is predicted to cost £156.95bn
The Midlands Economic Forum (MEF), which has produced new analysis on the controversial high-speed rail link, has also raised concerns that phase one of the scheme – which is set to link Birmingham and London – may not be complete until 2030.
Further concerns have been raised about whether HS2 will actually be able to make it to London Euston due to engineering difficulties. The MEF has suggested the main London hub could actually end up becoming Old Oak Common in West London, near Wembley.
Paul Forrest, the head of research at the MEF, told the Express & Star: "A high-speed rail link is quite important but it has to be cost effective, which these latest sums show HS2 is not.
"For the Black Country, Staffordshire, Shropshire, you need fast links to Curzon Street to make HS2 work but there is no direct link.
"We need a proper integrated transport system for the region."
HS2 Ltd, which is the company behind the high speed rail link, has defended its plans.
A spokesman for the firm said: “We do not recognise these figures or the analysis by the Midlands Economic Forum.
"The budget for HS2 was set at the 2015 Spending Review and it was set at £55.7 billion. Our challenge is to deliver HS2 to that budget, working with our supply chain to drive efficiencies and economies of scale across every part of the project.
“HS2 is a once in a generation opportunity to rebalance Britain’s economy and is expected to create around £92 billion in benefits across the UK. The new railway will transform journeys, improve reliability and give rail passengers thousands of extra seats every day.
"More than 100 towns and cities are set to benefit from the extra capacity that HS2 will bring, and all along the route local economic plans are being developed that ensure the whole country will benefit, including the Midlands.
"Birmingham will be at the heart of the new network, and HS2 will add £14 billion to the West Midlands economy, supporting 100,000 jobs.”