The Supreme Court of Canada cleared the way Thursday for a proposed multibillion-dollar class action lawsuit on behalf of some 100,000 cattle farmers hurt by the 2003 mad cow disease scare.

The country's top court has refused to hear an appeal by the federal government and Winnipeg-based feed company Ridley Canada, which both sought to derail the lawsuit.

As is usual, the court provided no reasons for turning down the appeal application.

At issue is whether farmers who suffered economic losses as a result of the 2003 border closure over BSE-contaminated cattle could sue for what they argue was negligent regulatory policy.

In 2007, the Ontario Court of Appeal cleared the way for much of the protracted lawsuit to proceed to the next step, which will determine whether the case can be classified as a class action.

Cattle farmer Bill Sauer, the lead plaintiff in Ontario, has argued that Ottawa introduced regulations in 1990 that specifically allowed the feeding of cattle parts to other cattle.

Bovine spongiform encephalopathy, also known as mad cow disease, is spread when live animals are fed parts of dead cattle mixed into their largely plant-based feed, usually brains and spinal cord material.

Mad cow disease in cattle has been connected to a similar illness that has killed hundreds of people all over the world, although not all scientists agree that consumption of beef from animals that died of mad cow disease invariably causes human variant Creutzfeldt-Jakob disease.

The proposed lawsuit says the 1990 Canadian regulations on feeding cattle came a full two years after Britain had banned the practice, and three years after Canada barred uncertified cattle imports from the United Kingdom because of BSE fears.

The Canadian government didn't explicitly ban the dangerous feed practices until 1997.

Co-ordinated suits from producers in Alberta, Saskatchewan, Ontario and Quebec are seeking at least $7 billion in losses and another $100 million in punitive damages.

There have been at least eight cases of mad cow disease in Canadian cattle since 2003, resulting in beef export bans and the slaughter of thousands of cattle.

With files from the Canadian Press