Six regional heads of Britain's biggest employers' group have urged the government to build the controversial HS2 rail project in full.
The call by the CBI chiefs comes amid a government-commissioned review which could lead to all or part of the high-speed rail network being scrapped.
The CBI regions were the East Midlands, West Midlands, Yorkshire and Humber, London, the North East and North West.
They said HS2 will bring benefits "far beyond its costs".
The statement claimed a scaled-back version of the controversial project "will not deliver the improved connectivity across the country that businesses are crying out for".
It continued: "HS2 will bring benefits to local communities far beyond its costs. It will create half a million jobs, stimulate house building along its route and support much-needed investment across the Midlands, North and beyond.
"It is the critical spine that will bring wider transport improvements like Northern Powerhouse Rail and the Midlands Rail Hub to life."
Northern leaders have also published a review recommending that the North and Midlands must take control of plans for a high-speed rail network in their areas.
The Northern Powerhouse Independent Review called for the establishment of a body named HS2 North, which would be at arm's-length from the government and be overseen by Transport for the North to ensure HS2 and Northern Powerhouse Rail are combined efficiently.
Chris Oglesby, chief executive of Manchester-based property firm Bruntwood and a member of the panel which oversaw the review, said: "Our review panel proposes that the North and Midlands must take control of the nation's high-speed network.
"HS2 and Northern Powerhouse Rail - a major priority of Boris Johnson and his government - are completely interlinked and a joined up approach is required to both and the upgrades to existing lines.
"Only by delivering an integrated high-speed network right across the North can a Northern Powerhouse vision be truly realised. Further delays and uncertainty are hugely damaging to the North and the country as a whole."
A review into whether to scrap HS2 was launched by Prime Minister Boris Johnson in August and is due to be completed shortly.
It is being led by Douglas Oakervee, a former chairman of HS2 Ltd - the taxpayer-funded firm building the railway - with Lord Berkeley acting as his deputy.
Recent figures compiled by HS2 Ltd show the railway could be delayed by up to seven years and run £26bn over budget, reaching a cost of £88bn.
Phase 1 of HS2 is planned to run between London and Birmingham. Current designs involve a second Y-shaped phase launching in two stages: Phase 2a from the West Midlands to Crewe followed by phase 2b from Crewe to Manchester, and Birmingham to Leeds.