With the GCSE results due to be released this Thursday, the CIPD and KPMG report only 24% of employers plan to hire 16 to 18 year-olds this quarter compared with 63% that plan to take on staff aged between 19 and 24.
The organisations' Labour Market Outlook shows almost two-thirds intend to take on older workers, but the number of 16 and 17 year-olds in employment has dropped by 18% in the past year - compared with a 2% increase for workers above pensionable age.
This year 20,000 16 and 17 year-olds report they have been unemployed for more than one year - marking a 100% increase from 2008.
Gerwyn Davies, CIPD public policy adviser, said: "School leavers seeking work this year face a difficult enough task finding an employer willing to take on young people, let alone find a job.
"These results suggest that Government policy needs to be changed to give similar help to unemployed 16 and 17 year-olds as that which is given to other targeted unemployed groups."
The news comes as the CBI calls for a Government subsidy to fund new apprenticeships as it claims "youth unemployment is reaching unacceptable levels".
Under the CBI's proposal, £125 million of the £500 million Government recruitment subsidy fund to help unemployed should be used to subsidise 50,000 new apprenticeships. Firms would receive a subsidy of £2,500 towards training each apprentice.
Richard Lambert, CBI director general, said: "Young people leaving education this summer face the toughest job market in a generation. We know from previous recessions a lack of employment after leaving education can damage young people's long-term prospects at a critical point as they move from education to the world of work.
"Young people are being hardest hit by unemployment, and the Government must increase the opportunities available to limit its scarring effects."
