The Professional Contractors Group (PCG) has pledged to fight any moves by the European Union to introduce the proposed Agency Workers Directive.
Contractors are angry at claims that the government plans to back the legislation, which would compel employers to give all freelance workers the same benefits as permanent staff from day one.
The PCG fears that the move - an attempt to prevent exploitation of temporary staff - would drive down rates in the sector and discourage businesses from using contractors.
"This is unnecessary regulation. If it comes in, it will make the use of freelance workers an unfeasible proposition," said PCG chairman Dr Simon Juden.
"We don't think it should happen at all, and if it does we certainly don't want it to apply to our members, who are mostly incorporated freelance contractors.
"Our sector simply doesn't need regulation to prevent workers from being exploited - it just doesn't happen."
The PCG is calling for more research to establish a true picture of the freelancer community across the EU. Juden claims the organisation has considerable cross-party support in the European parliament and is confident the EU will be forced to listen to its arguments.
"MEP Peter Skinner has already tabled a question calling for research. I am confident that with the weight of evidence behind us we can force a rethink," he added.
In the past fortnight other groups representing contractors and employers have also spoken out against the legislation, including the Association of Technology Staffing Companies, SME pressure group smallbusiness|europe, and contract recruitment firms Parity and Giant.
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