Some 200 people staged a sit-in outside the US State Department Monday, demanding that US President Barack Obama stop the controversial Keystone XL Pipeline.

Activists from environmental groups and civil society organizations held placards and shouted:"President Obama, stop the pipeline!"

The proposal under debate pertains to construction of a 1,179-mile (1,897 kilometer) portion stretching from Alberta to Nebraska.

Opponents of the pipeline, which would carry oil from Canada's tar sands to coastal Texas, say its environmental risks outweigh economic benefits, citing the impact on climate change and the potential for groundwater pollution should the pipeline break.

"We expect to see here what we have been seeing all across the country which is citizens coming in, sitting in, risking arrests to urge the State Department and President Obama to finally reject the Keystone XL Pipeline," Elijah Zarlin, one of the sit-in's organizers, told AFP.

The protest was held without incident.

President Obama expressed doubts about Keystone XL last month, saying it would create only 50 permanent American jobs.

Republican House Speaker John Boehner, however, has said the project would create tens of thousands of jobs.

The pipeline requires the president's approval because it crosses the US border.

Obama has previously put off a decision on the pipeline, waiting for the results of a study on the pipeline's environmental impact.

During a talk on climate change on June 25, Obama said that the pipeline should go forward "only if this project does not significantly exacerbate the problem of carbon pollution."

Supporters of Keystone XL insist that it would have a negligible impact on the environment.