Protests are expected in Washington D.C. today as environmental groups are set to rally against the construction of the Keystone XL tar sands oil pipeline. The line will stretch from Canada to the Gulf of Mexico.

Marchers will gather outside of the Ronald Reagan Building, where the State Department is due to hold a hearing about the pipeline. The organisers of the protest, Chesapeake Climate Action Network, have condemned the hearing over recent corruption claims linking a major lobbyist for the project to the Secretary of State.

Tar sands are an unconventional petroleum source, containing bitumen, which is a viscous form of petroleum generally known as tar or heavy crude oil. Alberta in Canada reportedly contains the largest deposits of crude bitumen in the world.