One in four employees now routinely works more than 48 hours a week.

The findings, which were released today by the Chartered Institute of Personnel and Development, showed a massive increase in the number of people affected by the "long hours culture".

Patricia Hewitt, trade and industry secretary, said: "We all recognise the damaging effect long hours can have on employees in both their work and family life.

"But according to the Labour Force Survey, a quarterly survey of 60,000 employees, the proportion of full time employees working over 48 hours a week has fallen from 23.5 per cent to 20.4 per cent in the past 6 years. The average weekly hours has also fallen by just over an hour over the same period.

"However, there are still far too men and women working long hours and suffering as result. Flexible working can help tackle the hours culture, it's why we introduced legislation in April to promote flexible working and enable employees to get a better work life balance.

"The culture is changing slowly, over 5 million people now have some kind of flexible working, but I want to help more people get the hours to suit them either formally through the new rights, or informally with their employers."

Forum Response: Chartered Institute of Personnel and Development

Mike Emmott, head of employee relations at the CIPD, said: "There is little support from the survey for arguments that the current option for employees to opt out from the 48 hour week should be removed.

"Half of those who work long hours say they do so entirely as a result of their own choice. They are just as satisfied as other people with their lives inside and outside work.

"More than half are either managers or professionals who should be well placed to exercise informed choices about their hours.

"Some employers are asking staff to sign an opt-out clause simply in order to take the issue of long hours off the table and avoid the possible need for record keeping, even though employees rarely or never work more than 48 hours for long periods. It would therefore be disastrous to remove the opt-out at a stroke."

"The overall trend in working hours among female workers is upwards. This is not however necessarily bad news.

"Relatively few of those working long hours are women. If efforts to secure equal treatment for women at work are to bear fruit we can expect to see their experience of work and working patterns aligned more closely with those of men.

"More women are now returning to work after having babies and having the opportunity to build careers. They also enjoy a strong position in the job market.

"The increasing number of female long hours workers is not surprising given that a higher proportion of them are managers and professionals, who tend to work the longest hours.

"As the service sector continues to grow and male-dominated sectors such as manufacturing, mining and agriculture continue to decline, this trend looks set to continue.

"The negative effects of working long hours are increasingly recognised. Most long hours workers report some kind of negative effect on job performance, one in four report damaging effects on their mental health in terms of stress or depression and many claim that long hours have put their relationships and health under strain.

"Clearly there can be important downsides to working consistently long hours and employers and employees both need to be aware of them.

"The new right to request flexible working will undoubtedly help employees to achieve the balance between home and work that best suits their circumstances and needs."

Forum Response: British Retail Consortium

Russell Hamblin-Boone, head of public affairs at the BRC, told ePolitix.com: "Retailers have pioneered changes in working practices to ensure the most flexible hours to meet the needs of staff and customers.

"Half of retail employees work part time and our stores offer working condictions that suit working mothers, returners to work and even the semi-retired.

"The BRC was consulted by the Cabinet Office for our expertise when it was developing new working patterns for the NHS."

Forum Response: Barclays

A spokeswoman for Barclays told ePolitix.com: "A truly equal and diverse work environment is a business priority for Barclays. We want to break the glass-ceiling for senior women and have leading-edge policies that encourage people from all backgrounds to want to work for Barclays and enjoy the experience when they do."

Forum Response: Institute of Directors

A spokesman for the IoD told ePolitix.com: "Official data show that the average hours for a full-time male worker is less than 40 hours (less than 35 hours for women) and surveys show that most 'long hours' workers do so voluntarily to further their careers and/or earn more money.

"The assertion that "Britain works the longest hours in the EU" is not strictly true (Greece works longer hours) and, globally, Britain has an 'average hours' culture rather than a 'long hours' culture."

Forum Response: Countryside Alliance

Simon Hart, chief executive of the Countryside Alliance, told ePolitix.com: "In rural communities the 'long hours' culture is especially prevalent, with farmers routinely working 60 hour weeks for less than the minimum wage.

"In fact, suicide rates amongst farmers are worryingly high - the Foot and Mouth crisis, BSE, swine fever - all of these catastrophes have taken their toll on the beleaguered farming community and many are leaving the industry because they cannot justify the pressure, stress and lack of economic viability of their situations.

"Awareness of this problem is increasing, but as well as offering support to the stressed out farming community, we need to see the industry getting the long term financial support it deserves.

"Long working hours are just a symptom of a far wider problem - they are a touchstone for an industry in crisis".