MONTREAL (Reuters) - Canadian companies have been reporting sturdy third-quarter profits, but the country's red-hot dollar is a trial by fire for those firms whose operating costs are in Canadian dollars.

The currency reached parity with the US dollar in late September and notched a fresh 33-year high against it last Friday. It closed at US$1.0393, making a US dollar worth 96.22 Canadian cents.

For companies such as forest products maker Tembec Inc or Air Canada, which have debt issued in US dollars, the Canadian dollar surge can translate into a fat currency translation gains.

For others, especially those with considerable Canadian dollar costs but US dollar revenues, the high-flying currency, colloquially known as the loonie, looks like a harbinger of tough times to come.

In its profit report, Maple Leaf Foods, one of Canada's biggest food processors, said the strong Canadian dollar was hurting its meat and bakery businesses.

"We're just scrubbing every corner of our business, looking for opportunities to readjust and realign our business, to compete in the North American market at (dollar) parity," chief executive Michael McCain said during a conference call.

Tundra Semiconductor cut its second-quarter revenue and profit forecasts, in part because its revenues are generated in US dollars but reported in Canadian dollars.

Canadian National Railway said a portion of its two percent drop in third-quarter net income stemmed from a stronger Canadian dollar and was affecting its outlook.

Agnico-Eagle Mines said its third-quarter profit fell as a stronger Canadian dollar pushed up the gold miner's costs.

The mood at Canada's manufacturers, which are concentrated in Central Canada, is growing blacker as the currency shines.

A Statistics Canada survey of 3,000 companies released last Friday showed that a greater proportion of manufacturers expect their production levels to fall in the fourth quarter from the third quarter, in part because of the strong Canadian dollar.

The survey was taken in the first two weeks of October, just after the Canadian dollar reached parity with its US counterpart.

"If you thought the pressures on exporters and Central Canada were bad this summer, wait for the data on the fourth quarter and early '08," wrote Andrew Pyle, Investment Executive at ScotiaMcLeod.

At Montreal-based Bombardier, pillar of Canada's aeronautical industry, the soaring dollar has workers fretting that Canadian production could be shifted outside the country to cut costs. Bombardier will not tip its hand, saying only that its profit strategy goes beyond management of currency changes.

"For some time, measures have been in place aimed at improving productivity on a continuous basis and not just strictly on the basis of a fluctuating Canadian dollar," said spokesman Jean-Philippe Cote.

With the bulk of Canada's third-quarter financial reports yet to come, analysts are assessing the Canadian dollar's impact on corporate profits.

At UBS Investment Research, analyst Fadi Chamoun expects the Canadian dollar to take a two Canadian cent bite out of third-quarter earnings per share at Canadian Pacific Railway, which he estimated would come in at C$1.19 a share, up 12 percent from a year earlier.