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Ontario Energy Minister Brad Duguid is pictured at a grand opening celebration of the completion of the Sarnia Solar Project in Sarnia, Ont., last October. (Dave Chidley/Canadian Press)

Higher-than-normal radiation levels have been detected in Ontario as a result of the nuclear crisis in Japan, but officials said Tuesday the increase is so small it doesn't pose a health risk.

Energy Minister Brad Duguid said levels have gone up slightly, but he didn't have any specific details on whether the increases were found in water, air or food.

"There has been some detection of some minor increase in radiation, but it's not anywhere close to something that would impact human health," Duguid told reporters. "It's not something that Ontario residents need to be overly concerned about."

The news comes one day after Japan increased the severity rating of the crisis at the tsunami-ravaged Fukushima Daiichi nuclear plant to the same level as the Chornobyl disaster.

The energy minister's office distributed information from the Canadian Nuclear Safety Commission and Health Canada on normal background radiation and some radiation that may "have been carried by the wind" from Japan to this country.

"Natural background radiation varies from location to location, but Health Canada's data does not show an increase over and above the normal day-to-day fluctuations," the safety commission said.

"However, very minute levels of isotopes in the radiation have been attributed to the release in Japan."

The actual increase in radiation "is so small that it is extremely difficult to measure against normal background radiation," the commission said. "The findings from these detectors further confirm that radiation doses do not pose a health risk to Canadians."

Dr. Arlene King, Ontario's Chief Medical Officer of Health, said all imported and domestic products tested by the federal government are below Health Canada's action levels for harmful radiation.

"Based on current information, I am of the view that there is no health risk for Ontarians from the damaged nuclear facility in Japan," King said in a statement.

Ontario Environment Minister John Wilkinson said there are no radiation problems with the province's drinking water.

"The water in Ontario is safe, but given the situation in Japan we are using increased vigilance," he said.

Agriculture Minister Carol Mitchell said it was up to the Canada Food Inspection Agency to determine if there was any radiation in food or milk sold in Ontario.

"All of the milk that is sold within Ontario is sterilized, pasteurized," said Mitchell.

Ontario's New Democrats said they couldn't believe the provincial government knows so little about radiation levels a full month after Japan's nuclear crisis began.

"It's quite disconcerting," NDP Leader Andrea Horwath said. "The people of this province just want to know their water is safe, their food is safe, their milk, and it's quite surprising that we couldn't get the answers out of the government today."

The NDP pointed out that elevated radiation levels already have been reported in several eastern American cities, including in milk from Vermont, Arkansas, California and Arizona, and in the water in New Jersey, Pennsylvania, Idaho and Tennessee.

"There's obvious monitoring going on in other jurisdictions," Horwath said. "If they're doing testing and letting people know what's happening, Ontario residents should expect nothing less."

With files from The Canadian Press