Plans are being drawn up by the European Commission to give temporary workers in the UK the same conditions as permanent employees.
The proposal will look at benefits such as pensions, holiday pay, sick pay, interest-free loans and share schemes for workers across the European Union.
The UK government said that while it believes agency workers should get a fair deal, legislation introduced by the EU should not conflict with UK policies and the need for flexibility in the labour market.
Meanwhile, John Monks, general secretary of the Trades Union Congress (TUC) said: "'Temporary workers in the UK face not only substantial job insecurity but they also often receive far less favourable treatment than those they work alongside. Unequal treatment for temporary workers is as bad for business as it is unfair to workers themselves."
Many temporary workers are currently paid less than permanent staff, and may get no sick or holiday pay.
The European Commission plans to bring in legislation dealing with the issue in mid-March.