Media playback is unsupported on your device Media caption Penny Cook has asked her part-time employer for more hours but has been refused

One in 10 of all workers in the UK is now officially underemployed, according to a study from the Office For National Statistics (ONS).

It says 3.05 million workers want to work more hours each week, out of a total workforce of 29.41 million.

The number of workers in this position has shot up by 980,000 in the four years since the start of the economic recession in 2008.

Most of the underemployment is concentrated among part-time workers.

This problem of underemployment seems to particularly affect the poorer parts of society

The main reason for the growth of underemployment has been the economic downturn of the past few years.

"During this period many workers moved from full-time to part-time roles and many of those returning to work after a period of unemployment could only find part-time jobs," the statistical office said.

"Of the extra one million underemployed workers in 2012 compared with 2008, three-quarters were in part-time posts."

The ONS said 1.9 million of the underemployed were in part-time jobs and this meant, in turn, that 24% of all part-timers wanted more work.

By contrast, only 5.5% of full-time staff said they wanted to work more hours.

Each quarter, as part of its Labour Force Survey (LFS), the ONS asks respondents a series of questions about their willingness and ability to work more hours.

Someone is counted as underemployed if they are working fewer hours than they would like.

Image caption The underemployment survey attempts to show the number of people in employment who wish to work longer hours. The yellow bars show that since the start of the economic downturn in 2008, the number of underemployed has risen by 47% despite a recent decline in the jobless rate. Image caption The rapid increase in the number of those underemployed is directly related to the weak economy. With fewer jobs available and fewer hours on offer, more people are working part-time. previous slide next slide

The growth of underemployment has gone alongside a big fall in the real value of earnings, the ONS said, which have been outstripped by inflation in recent years.

Jane Tomlinson, a part-time worker from Oxford, told the BBC what it had been like to be underemployed for the past year.

"I work only 15 hours a week paid work for a charity as communications manager," she said.

"I don't actually want a full-time job, but I need more than 15 hours a week, so I pick up a bit of copywriting work here and there as I can find it.

"But month to month it's really tough as I make only just enough to pay the bills. Thank goodness my husband has a job," she added.

'Half-time salaries'

Caroline Parre, an academic from Birmingham, said for the past three years the recession had prevented her hours being extended.

With part-timers we can contract and expand our workforce relative to increases and decreases in orders received, Colin Johnson, An employer from Lincoln

"Recruited to set up a research centre, the expectation had always been the part-time job would convert into full-time employment. The recession has changed that hope," she said.

"There is danger in the situation: to enable the success of the venture I have, voluntarily, worked full-time hours on a part-time salary, in the hope and belief that efforts would be rewarded.

"Efforts, of course, are not rewarded, and employers find themselves in the happy position of paying full time workers half-time salaries," she pointed out.

But a spokeswoman for the Department for Work and Pensions (DWP) said the figures showed that three quarters of all part-time staff appeared to be content.

"Part-time working suits millions of people and gives others the skills and experience to find a different job or take advantage of longer hours when they are available," she said.

"For many people it is an important step to full-time work and coming off benefits."

This was backed up by Colin Johnson, who runs a mail order company in Lincoln and who told the BBC his staff were happy to work part-time.

"All of my employees are technically part-time. Some are working mums who work around schooling," he said.

"With part-timers we can contract and expand our workforce relative to increases and decreases in orders received, and we can dovetail staff to deal with peaks on the phone.

"Prior to this way of working we would have out-sourced, so these are new jobs," he added.

Self-employed

The ONS explained that most of the rise in underemployment took place between 2008 and 2009, when the recession first gripped the UK economy.

Media playback is unsupported on your device Media caption ONS statistician Jamie Jenkins: "Underemployment has gone up by one million people since the economic crisis"

Since then it has still been rising, though more slowly then before.

According to the ONS analysis, the problem is worst among the lowest paid, young workers and those in low-skilled jobs, such as labourers, cleaners and catering staff.

The shortage of work has also led to a big rise in the level of underemployment reported by the self-employed.

They are now even more likely to report being underemployed than those who work for others.

However the precise reasons for individuals being underemployed can vary.

The ONS said these reasons could include:

employers only being able to offer a few hours of work each week

workers, such as bar staff, being in jobs where they are only required for a few hours a day

personal circumstances changing so that someone now wants to work more hours then before

people settling for a part-time job as second-best when they would much rather have a full-time one

Labour market economist John Philpott said: "Approaching one in five economically active people are struggling in today's 'no or not enough work' economy.

"Add in the effect of falling real take-home pay for the vast majority of people in work and it becomes clear how much distress is being suffered."

The TUC's general secretary, Brendan Barber, said: "Being underemployed carries a huge pay penalty that puts a real strain on people's finances.

"Long periods of underemployment can cause longer term career damage, which is particularly worrying for the one in five young people currently trapped in it."