Some major US retailers are the latest to set Alberta oilsands in their sights.

The Walgreens drugstore chain is switching fuel suppliers for its delivery trucks to those that don't use oilsands crude.

Levi Strauss won't go as far as to say it's boycotting, but the company is asking suppliers to reduce their emissions and use clean and renewable fuel sources.

Gap and Timberland are also making moves to avoid oilsands crude, giving preference to fuel providers who use lower-carbon intensive fuels.

The environmental group organizing the action says more Fortune 500 companies are getting ready to sign on.

A full-on boycott may be impossible, though.

"In western Canada for example, about 50 per cent of our fuel supply comes from the oilsands. So 50 per cent of the gasoline and diesel fuel that everyone buys at the pump comes from the oilsands and and it's mixed up with the conventional oil supplies that we have. So you can't differentiate, you can't pull those molecules apart," says Janet Annesley with the Canadian Association of Petroleum Producers.

Premier Ed Stelmach is concerned and says he will be writing letters to the CEOs of each company.

"Unfortunately, these retailers have chosen a course of action without first talking to us about our environmental commitment and the efforts of thousands of Albertans working for government, industry and academic institutions to reduce the impact of oilsands development," said Stelmach.

The public policy advocacy group, Alberta Enterprise Group is urging Canadians to boycott companies that target oilsands fuel.

" This campaign will do nothing to improve the environment. If a company like the Gap wanted to do something to better the enviroment, they would shut down all their stores in Canada," says AEG president Tim Shipton.

This latest move is part of a growing international movement to put economic pressure on the industry, such as the Rethink Alberta campaign in the U.S. and England, which targets tourism by suggesting the province's resource regulations are damaging its scenic beauty.



