NEWARK, N.J. -

The U.S. attorney in New Jersey said Thursday that he is investigating the shutdown of highway lanes that may have been closed by Gov. Chris Christie's administration for political retribution.

A spokeswoman for U.S. Attorney Paul Fishman said in a statement that the Port Authority's inspector general referred the matter to Fishman's office.

Fishman said in a statement that his office is "reviewing the matter to determine whether a federal law was implicated."

Christie has apologized and said he was "embarrassed and humiliated" by his staff but had no idea his aides may have closed highway lanes to exact political retribution.