(Reuters) - Canada's Silver Wheaton Corp (>> Silver Wheaton Corp.) , which provides financing to miners in exchange for the right to buy a share of their future production, reported a 15 percent fall in profit, hurt by higher cost of sales and lower commodity prices.

The company said on Tuesday it expects federal and provincial tax of about C$190 million ($145 million), resulting from Canada Revenue Agency's proposal to tax about C$715 million of income earned by the company's foreign units between 2005 and 2010.

The company added it will defend its tax filing positions vigorously.

The company, which provides financing to companies such as Goldcorp Inc (>> Goldcorp Inc.), Primero Mining Corp (>> Primero Mining Corp) and Barrick Gold Corp (>> Barrick Gold Corp.), said average realized sale price per silver equivalent ounce sold fell more than 17 percent to $16.38 per ounce in the second quarter.

Gold and silver prices have been tumbling as investors shift to higher yielding assets in anticipation of a rate increase by the U.S. Federal Reserve.

Silver Wheaton's net profit fell to $53.7 million, or 13 cents per share, in the quarter ended June 30, from $63.5 million, or 18 cents per share, a year earlier.

Revenue rose 10.7 percent to $164.4 million.

Up to Tuesday's close, company's Toronto-listed stock had fallen 42 percent in the last 12 months, while the U.S.-listed stock fell 51 percent.

(Reporting by Anannya Pramanick in Bengaluru; Editing by Don Sebastian)