The number of men aged 55 to 65 not in work has doubled in the past 20 years.
A report by the Institute of Directors found that while many men may have fallen victim to age discrimination, it is not the main reason behind the figures.
And author Richard Wilson warned the trend may be aggravating skills shortages, causing difficulties for business.
He concluded that age discrimination legislation would be ineffective. “Experience suggests that such legislation is unlikely to be effective in promoting the employment of older people.”
Instead, Wilson recommended a range of procedures.
“The Government must keep the cost of labour low. In particular, it should avoid introducing measures that increase the cost of employing part-time staff – a popular form of employment for older people,” he said.
Wilson also advised the Government to “encourage personal pensions or keep the cost of stakeholder pensions low” in response to 45 per cent of employers being more inclined to hire an older person if they did not have to contribute to their pension.
Other reasons given for the decrease in older men in the workforce include the prevalence of occupational pensions and early retirement, industrial restructuring and a reduction in the demand for unskilled labour.
The study found that in 1979 just over one fifth of men aged 55 to 65 were not employed. The proportion in 2000 is double that.