UK men with full-time jobs work the longest hours in Europe, because the UK is the only EU country that allows workers to opt out of the 48-hour limit on the average working week.
This restriction on hours is widely ignored and only a minority of employees know their working time rights.
TUC general secretary Brendan Barber said, "The UK is the only EU country that allows everyone at work to sign away their working time rights, and there is wide evidence this is not a free choice for the majority of long-hours workers.
"Official figures show that two thirds of those who work more than 48 hours a week would like to work fewer hours. TUC polling has suggested that one in three of those who signed the opt-out were given no choice, and that two out of three people who work more than 48 hours have never even been asked to sign away their long-hours protection.
"Employers have argued that working more than six eight-hour days a week should be a matter of free choice, but this research shows that too many employers cannot be trusted and may put unfair pressure on their staff. The only way to tackle our long hours culture is to end the opt-out."
The EU will shortly start a review of the UK opt-out. The TUC believes the opt-out should be stopped and that a 48-hour limit on the average working week should be introduced.
A Labour Force Survey found that four million white-collar workers work more than 48 hours a week on average and a study for the Department of Trade & Industry found that 16% of workers surveyed work more than 60 hours a week compared to just 12% of all UK workers in 2000.