A leading centre for independent economic research has said the best evidence currently available suggests a 50p tax rate backed by Labourwill raise "little revenue" and make a "marginal contribution" to reducing the budget deficit.
The signatories of a letter from business leaders - in which they criticise Labour's 50p tax plan - include Sir Stuart Rose, the chairman of Ocado, Sir Ian Cheshire, the chief executive of the DIY giant Kingfisher, and Neil Clifford, the chief executive of the footwear retailer Kurt Geiger.
Ed Miliband answered questions for the first time this afternoon about his plans to re-introduce the 50p rate of income tax.
Politicians at both ends of the political spectrum need to be more honest about the true motivations behind their tax policies.
Ed Balls has said Labour would restore the 50p tax rate for those earning over £150,000 if the party wins the next election.