Nebraska officials said Friday that an oil spill from the Keystone pipeline in South Dakota won't affect their decision to approve or deny a route for the related Keystone XL project.

A spokeswoman for the Nebraska Public Service Commission said that commissioners will base their decision solely on evidence presented during public hearings and from official public comments.

Supporters and opponents of the project argued their cases to the commission at a four-day hearing in August.

A Nebraska law approved in 2011 prevents the commissioners from factoring pipeline safety or the possibility of leaks into their decisions. Lawmakers argued at the time that pipeline safety was a federal responsibility that pre-empts state law. Opponents say oil interests lobbied for the restriction.

A federal pipeline safety agency has sent technical experts to the site of an estimated 210,000-gallon oil spill from the Keystone pipeline in South Dakota.

A Pipeline and Hazardous Materials Safety Administration representative said Friday that the agency's investigation is ongoing.

TransCanada Corp. crews shut down its Keystone pipeline Thursday after a drop in pressure was detected from the leak south of a pump station in Marshall County.

State officials say the buried pipeline leak is on agricultural land and don't believe it has polluted any surface water bodies or drinking water systems.

The pipeline delivers oil from Canada to refineries in Illinois and Oklahoma. The leak was found just days before Nebraska regulators are to announce whether they approve an expansion of the Keystone system

TransCanada says it expects the pipeline to remain shut down as the company responds to the leak.