This new polling will be of significant interest to the ongoing government review.
Most business leaders in London believe the HS2 high-speed rail project costs too much and will cause too much disruption while being built, a study suggests.
A survey of 500 businesses in the capital indicated that only two out of five believe the line would boost the UK economy.
The London Chamber of Commerce said its poll found that nearly three quarters of business leaders think HS2 costs too much and two thirds feel its construction has or will cause too much disruption. Almost half did not believe that HS2 was necessary.
Peter Bishop, chief executive of London Chamber of Commerce, said: "With nearly three quarters of businesses voicing concern about the growing cost of the project, this new polling will be of significant interest to the ongoing government review.
"It is important to note that London businesses see merits in the project for both London and the UK.
"However, majority concern about its necessity, costs and disruption, leave a clear challenge for the promoters of the project to effectively convey that the project is worth its mounting cost."
But Northern Powerhouse Partnership director Henri Murison said: "The Chambers of Commerce across the North and their members are united and clear - we need both HS2 and Northern Powerhouse Rail delivered in full to rebalance the UK economy and create opportunities for business investment and growth.
Alan Jones is the PA industrial correspondent.