The UK economy could receive a £580 billion shot in the arm if more businesses were started by women, ethnic minorities and people living outside London and the South-east.
However, according to the CBI, Government attempts to boost enterprise in these groups are failing.
The most active entrepreneurs continue to be white men in London and the Home Counties.
According to the CBI, the percentage of self-employed women has fallen from 27.8 per cent in 2000 to 26.7 per cent.
Over 2.7 million men work for themselves compared to less than one million women. Businesses started by men, on average, achieve three times the turnover of female startups over the first three years.
The percentage of ethnic minorities working for themselves has also decreased - from 7.4 per cent of businesses in 2000 to 7.0 per cent this year. This figure is also fore-cast to drop to 6.2 per cent by 2020, the CBI said.
Marla Nelson, assistant director of the Coventry-based Women's Business Development Agency (WBDA), said she was unsurprised by the figures.
Ms Nelson said WBDA and Women in Rural Enterprise - the two main providers of women's enterprise support in the West Midlands - were working closely with the regional development agency Advantage West Midlands.
AWM was currently developing a system to make sure under-represented groups received better business support.
However, she said the Government could do more to break down barriers for women.
"The two main obstacles are access to finance and affordable childcare," she said.
Ms Nelson's comments were backed up by a separate study released yesterday.
A poll of 1,000 women by Red Magazine suggested many women who want to be their own boss are put off by the financial risk.
More than four out of five had thought of starting a business venture, but most said they had been put off by the financial risk or lack of money.
Almost half of those questioned said they believed they could do a better job than their boss.
According to the CBI , if the UK as a whole - particularly women and ethnic minorities - set up businesses at the same pace as London and the SE, one million new firms would be created.
If each achieved the average UK business turnover of £578,000, this would equate to a £580 billion boost for the UK economy, the CBI said.
"There is a huge, untapped well of entrepreneurial potential in Britain which would boost the economy and raise the living standards of millions of people if it could be unlocked," said CBI director-general, Sir Digby Jones.
"More women, ethnic minorities and people across the entire length and breadth of the UK, including its most far-flung corners, must be helped with the skills, self-belief and support to start and grow a business.
"Yet the trend is going in the wrong direction and the Government must address the problems and causes to better tailor its efforts to solve them.
"Boosting enterprise requires a tax and regulatory regime that supports risk taking. There must be proper support for businesses, and, perhaps most importantly, the Government should invest in the transport infrastructure to ensure no region of the UK is left behind."
The percentage of self-employment in the white community rose from 7.1 per cent in 2000 to 7.8 per cent. It is projected to be 9.6 per cent in 2020.
Business start-up rates in deprived areas are well below the UK average - approximately 37 adults per 10,000 compared to 42 per 10,000 for the rest of the country.
It also revealed that London has more businesses than Wales, Scotland and Northern Ireland combined.
