By Paul Willcocks

VICTORIA, British Columbia, Aug 3 (Reuters) - New patents on human genes threaten to inflate health care costs and deny patients life-saving tests and treatments in Canada's already troubled medical system, provincial leaders warned on Friday.

The premiers of Canada's 10 provinces, whose debates over the country's public health care system have usually focused almost entirely on issues of funding, surprised observers by adding gene patents on Friday to list of issues they want the country to deal with.

"The implications for the future are huge, both on access and costs," Ontario Premier Mike Harris told reporters at the end of the annual provincial leaders' summit in Victoria, on Canada's Pacific coast.

Harris has agreed to prepare a report for the premiers when they hold a special meeting on the health care system in January.

Patenting genes has become a multimillion-dollar business internationally, and has fueled global debate over when and if private companies should be given exclusive rights to bits of the DNA code that make people human.

Harris cited a Canadian patent received by U.S. biotech firm Myriad Genetics Inc. (MYGN.O) for commercial use of the BRCA gene, which can help identify the risk of hereditary breast cancer. That form of breast cancer accounts for for up to 10 percent of all cases.

Ontario hospitals have been using the gene in their own tests to identify women who are at increased risk, Harris said.

Myriad, whose patent runs until 2015, charges about C$3,800 for the same test performed by Ontario hospitals. In the United States, the company has enforced its patent to ensure that only its test is used commercially.

"Is it going to be available to the world? This is the concern," said Harris, warning he was concerned the escalating costs would add to already-mounting financial pressures on the nation's publicly funded medical system.

Critics of gene patents charge they restrict needed medical research. The American College of Medical Genetics has called for a ban on the patenting of human genes. It says the resulting monopoly could result in exorbitant costs and limited access.

Biotech companies argue that the costly, life-saving research that results in medical treatments can only be done if they have the ability to protect intellectual property rights and profit from their work.