As secretary of state, Clinton presided over years of study of the Keystone XL pipeline that would send Canadian crude oil to US refineries. The project is vehemently opposed by environmental groups and liberal Democrats.
Clinton had used her former position as a rationale for not weighing in, saying she wanted President Barack Obama's administration to finalise its assessment on the project.
But during a campaign event in Iowa, she described Keystone as "a distraction from the important work we have to do to combat climate change, and, unfortunately from my perspective, one that interferes with our ability to move forward and deal with other issues. Therefore, I oppose it," she said yesterday.
The 1,179-mile (1,900-km) TransCanada-built pipeline would transport crude from oil sands in energy-rich Alberta province to a network of pipelines that reach across the US to the shores of the Gulf of Mexico.


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