Employers and Trades Union groups have clashed over draft European Union legislation that would give temporary staff the same rights as full-time workers.
The EU's proposals would oblige firms to give temporary workers the same pay and conditions as full-time staff after six weeks' employment.
The Confederation of British Industry (CBI) has warned that the proposals would deter many employers from taking on temporary workers, destroying thousands of jobs.
According to a CBI survey carried out with employment agency Pertemps, 47 per cent of employers would take on fewer temporary workers if the law were adopted.
The UK is thought to have the highest number of temporary workers in Europe.
At present, temporary staff in the UK are not entitled to the same range of pay and holiday benefits as their full-time counterparts.
Agency workers, casuals, home workers, freelancers and other groups such as seafarers, the clergy and some civil servants, have no legal right to unfair dismissal protection or maternity and paternity leave.
According to the TUC, this leads to "ludicrous anomalies" where, for example, female workers have the right to statutory maternity pay but no right to maternity leave, and male workers are entitled to statutory paternity pay but have no right to return to a job after taking the leave.
The TUC claims that employers are using less permanent forms of working as a way of avoiding giving staff decent pay and protections.
Unions are demanding that all workers are entitled to same basic rights at work regardless of their type of employment. These include unfair dismissal protection, family friendly rights, parental leave and time off for dependents, working time protection and holiday entitlements, as well as trade union rights.
But the CBI believes that equal pay and conditions should be introduced only after a full year's employment.
"If the EU is serious about economic reform it should not be trying to drag the UK's flexible and successful labour market in the direction of other countries where they have high unemployment," said CBI director general Digby Jones.
But the TUC dismissed the CBI's warning. "There is absolutely no factual evidence for the claim that extending these rights to agency temps will cost jobs," said TUC General Secretary, Brendan Barber.