The Canadian government is acting as a representative of major oil companies by lashing out at opponents of a tar sands pipeline, an advocate said. Canadian Natural Resources Minister Joe Oliver wrote an article in The Globe and Mail newspaper saying the country\'s energy markets are being held hostage by \"environmental and other radical groups\" trying to thwart efforts to diversify the economy. The government scheduled public hearings Tuesday over plans by Canadian pipeline company Enbridge to build its Northern Gateway pipeline, which would carry as much as 500,000 barrels per day of crude oil from tar sands projects in Alberta to the Canadian west coast and ultimately to Asian markets. Critics consider Alberta crude one of the dirtiest forms of oil in the world. Opponents of the Northern Gateway are worried about the potential damage to the environment. Susan-Casey Lefkowitz, director of international programs at the National Resources Defense Council, complained that rather than showing environmental advocates respect, the Canadian government has resorted to name-calling. \"I say that care for our planet and our health makes sense and is not \'radical,\'\" she said in a statement. \"Wanting to fight climate change in the face of the violent storms, floods, droughts, and fires that we have experienced in just the last year in North America makes sense and is not \'radical.\'\" A similar debate is under way in the United States over TransCanada\'s plans to build the multibillion-dollar Keystone XL pipeline. That pipeline would bring Alberta crude to refineries along the southern U.S. coast.