Confirmation of a case of mad cow disease in Canada has resulted in plummeting shares within the meat processing and manufacturing industries.

In addition, shares in hamburger chains such as McDonald's dropped as much as 7 per cent in the US overnight.

Britain suffered the worst outbreak of mad cow disease among western countries in recent years, prompting bans on imports of its beef to Europe. The human variant of the condition, Creutzfeldt-Jakob disease (CJD), is passed on to humnas from infected meat.

US Department of Agriculture (USDA) officials on Tuesday temporarily halted improts of Canadian cattle, as well as processed meat over fears that BSE, or bovine spongiform encephalopathy, would spread across North America.

The USDA is placing Canada under its BSE restriction guidelines an will not accept any ruminant products from Canada pending further investigation.

"We are dispatching a technical team to Canada to assist in the investigation and will provide more detailed information as it becomes available," said agriculture secretary Ann Venneman.

In 1997, the US Food and Drug Administration prohibited the use of protein from other mammals in the manufacture of animal feed intended for cattle to stop the way the disease is thought to spread.

The US said that during last year it tested 19,990 cattle for BSE, using a targeted surveillance approach designed to test the highest risk animals.