Keystone XL pipeline protesters encircle White House
Thousands of protesters opposed to a controversial pipeline project surrounded the White House on Sunday.
Canadian company TransCanada is seeking permission to build the 1,600-mile (2,700km) Keystone XL pipeline from Alberta to the Gulf coast in Texas.
Environmentalists are opposed to the project because of the method used for extracting petroleum from Alberta’s oil sands.
They are also concerned by the risk of pollution on the pipeline route.
The proposed pipeline would pass south from Alberta through the US states of Montana, South Dakota, Nebraska, Kansas and Oklahoma before ending up at refineries in Texas.
Environmental groups say that extracting oil from the sands would generate huge greenhouse gas emissions, and that any accident on the route could be disastrous.