European employment ministers are meeting today to decide whether to adopt plans to grant new employment rights to temporary workers.
A proposed EU law would give temporary staff, such as those registered with employment agencies, similar rights to permanent workers.
If adopted, the agency workers directive would prevent employers giving temporary staff less pay, holidays and pension provision than that provided to workers employed on permanent contracts.
But the British government has signalled its opposition to the plans, which ministers fear would undermine the country's flexible labour market and hit jobs.
Their concerns are shared by business groups, with the Confederation of British Industry (CBI) today claiming the proposals could lead to the loss of a quarter of a million UK jobs if adopted.
CBI deputy director general John Cridland told the Today programme: "The directive might work in Brussels, it won't work in Britain. It would cause employers to use 250,000 fewer agency workers.
"We can have sensible legislation for agency workers, not legislation that's written in Brussels for a continental labour market and isn't appropriate in the UK," he added.
However trade unions have rejected the arguments put forward against the proposed changes, claiming it is unfair for temporary workers to be deprived of the same rights as permanent staff.
Speaking about the issue earlier this week, TUC general secretary Brendan Barber said: "Too many unscrupulous bosses are replacing permanent staff - with reasonable terms and conditions - with insecure agency staff.
"They regularly earn less than directly employed staff, are not allowed to benefit from an employer's contributions to a pension scheme, are given less holiday, little if any access to training, and tend to get no contractual sick pay," he added.