The expected benefit-cost ratio of the HS2 has been revised down in the Government's latest report, falling from £2.50 benefit for every pound spent to £2.30.
It attributed the revision to a £10 billion increase in the scheme's projected £42.6 billion cost, which was made earlier this year.
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The letter was signed by the CBI, British Chambers of Commerce, the EEF, the Institute of Directors and the Federation of Small Businesses.
A spokesperson said Rory Stewart's remarks were in line with the British government’s stated position.
The minister's intervention will come a week after Trump decertified the landmark agreement claiming it was not in the US national interest.