A Federal Labor Government would put a freeze on companies entering the Comcare scheme until a new national workers' compensation framework is developed.

Deputy Leader Julia Gillard told a Sydney forum last week that Comcare's financial strength is being tested as riskier industries join the scheme, which was originally designed for white-collar public servants.

Labor has pledged to reform Comcare by negotiating with state governments to create a new national agreement on workers' occupational health and safety. Labor also wants to examine how the scheme is financed and how Comcare is affected by the addition of private companies.

Large businesses prefer Comcare - which now covers more than 20 companies - over state government schemes because payouts are capped at a lower rate and premiums are cheaper.

Another seven companies were admitted to Comcare just days before the federal election was called.

The influence of unions is also diminished under the Comcare system. Instead of having an automatic right of entry to investigate workplace safety, unions must give 24 hours' notice. Unions and Labor say the system compromises worker safety.

Australian Lawyers Alliance President Ian Brown says any national system would be flawed, as politicians would inevitably choose the cheapest and most effective model at the expense of sound policy.

But Ms Gillard says streamlining workers' compensation laws would be a priority for a Labor government, as inconsistencies between state schemes mean fewer rights for employees and reduced safety standards and compensation payments.

Costs imposed by red tape are also a burden for businesses juggling separate state schemes.

Earlier this year a union-backed action to prevent construction giant John Holland from moving to the federally administered system was rejected by the High Court. John Holland expects to save about $8 million in premiums under Comcare.