Almost half of recent graduates are in jobs which do not need a higher education background, new figures have shown.
An expert said the level of under-employment revealed a "massive waste" of investment in skills.
The Office for National Statistics (ONS) said there had been an upward trend in the proportion of recent graduates working in non-graduate jobs - up from 37 per cent in 2001 to 47 per cent this year, with most of the increase happening since the 2008/09 recession.
The figures also revealed that almost nine out of 10 graduates were in work, compared to an employment rate of 83 per cent for those educated to A-level standard, 76 per cent for GCSE, 70 per cent for other qualifications and 47 per cent for those with no qualifications.
Annual earnings for graduates increase at a faster pace as they become older, before levelling out in their late 30s at a median level of £35,000 a year, well above those without a degree, the study found.
People with a degree in medicine or dentistry had the highest employment rate of all graduates at 95 per cent , followed by those with media and information studies degrees (93 per cent), although pay rates varied.
Medical graduates had the highest median pay at £45,600, while media and information studies graduates had the lowest, at £21,000.
Dr John Philpott, director of The Jobs Economist, said: "The pre-recession rates of underemployment of graduate skills in the UK economy were already disappointing - the post-recession rates represent an alarming jump in under-employment and a massive waste of investment in skills."
Steve Radley, director of policy at EEF, the manufacturers' organisation, said: "Today's figures show that graduates have not escaped the squeeze on pay but they also highlight the major impact that subject choices have on earnings. Graduates in engineering are the second highest earners and those in physical sciences earn far beyond average also.
"We need a concerted effort to get more young people studying the science and engineering degrees that will drive our economy forward and more of them taking up well paid opportunities."
TUC general secretary Frances O'Grady said: "While university leavers are still better paid and more likely to have a job than non-graduates of the same age, their prospects are worsening, just as their debts are soaring.
"Having got themselves tens of thousands of pounds worth of debt, nearly half of all recent graduates are doing lower-skilled jobs. This is in turn pushing young people who don't have a degree out of work altogether.
"The Government's approach of making young people pay more to get less from higher education is deeply unfair and makes no economic sense. Ministers should admit that 'any old job' is not good enough for heavily-indebted graduates and start prioritising high-quality job creation."