WASHINGTON (Reuters) - The U.S. State Department is looking into whether Nebraska's approval of an "alternative" route for TransCanada Corp's <TRP.TO> Keystone XL pipeline through the state will require additional federal permitting, a spokesperson said.

"We have heard about a possible modified route, and we are in the process of gaining more precise information in order to determine if there will be any permitting impacts as a result of those changes," the spokesperson said, asking not to be named.

(Reporting by Valerie Volcovici; Writing by Richard Valdmanis; Editing by Andrew Hay)