The TUC has published the results of a survey of 2,500 agency workers in the run-up to the closing date of a government consultation on whether agency workers need more protection.

And while many agency workers are happy and content, the TUC says others experience poor treatment, do not know their legal rights and support a legal right to be given the same pay and conditions as the permanent staff with whom they work.

The poll, carried out by YouGov, found that 56 per cent don’t have the same holiday rights as permanent staff, even though a quarter have had assignments lasting more than six months, and 61 per cent say they don’t have the same sick pay rights as permanent staff.

It also appears that being an agency worker can result in employment limbo – half say that neither the agency nor the employer provides them with training that helps their career and 46 per cent say that working through an agency makes it harder to complain if anything goes wrong at work.

While acknowledging that the survey did not adequately represent those on the minimum wage, it seems that problems may be even worse for them – only 37 per cent say their agency has always treated them fairly, 61 per cent say working through an agency makes it harder to complain and 60 per cent say they’ve had jobs where the employer was trying to get work done on the cheap.

The TUC says unions do not oppose agency work. The survey confirms that it suits many people, with 27 per cent saying they prefer agency work even though they could get a permanent job and nine per cent saying they can’t or don’t want to work permanently.

Many employers use agency work appropriately, with 19 per cent using it to cover absent staff, a further 18 per cent using agency workers to cope with a busy period and 17 per cent using agency workers for a special project.

But the poll also reveals a dark side to agency work, with 26 per cent of staff saying the employer always uses agency workers for the job they were doing and 14 per cent saying they were replacing permanent staff.

And as the poll sample does not include the most vulnerable agency staff, such as migrant workers and others without internet access, the TUC says problems are likely to go much deeper.

The poll sample contains just six per cent on or below the minimum wage, while the official Labour Force Survey (LFS) reports 25 per cent of agency workers on the minimum wage.

The LFS finds that there are just over 250,000 agency workers, while trade body, the Recruitment and Employment Confederation, claims that that there are over one million agency workers. If this figure is accurate, it suggests that many agency workers – most likely to be vulnerable workers – do not show up in official surveys.

TUC General Secretary Brendan Barber said: “Up to now arguments about agency working have been strong on anecdote. This poll now provides a wealth of hard data.

“First it tells us that no-one should generalise about agency working. Some people enjoy the life and are happy with their agency. Many employers use it responsibly to cover for absence or cope with extra work.

“But even though our poll will not have captured the experience of many of the most vulnerable workers, it still reveals abuse and bad treatment for a significant proportion of agency workers.”

The TUC says that it will call on the government to licence all employment agencies and guarantee equal rights for agency workers and permanent staff.

“This won’t stop responsible employers using staff from responsible agencies, but it will end the temptation for bad employers to use agency staff to get round their legal obligations to permanent employees,” added Barber. “Responsible agencies should come out of their state of denial that bad practice happens, and join with us in trying to raise standards.”