The Interior Department's top watchdog has referred an investigation into Secretary Ryan Zinke to the Justice Department, raising the prospect that criminal violations have been uncovered, the Washington Post reported on Tuesday.

The Interior Department's inspector general has been looking into several inquiries involving Zinke, including accusations over his wife's travel and a land deal with a property development group backed by the chairman of the oilfield services company Halliburton Co. The Post cited anonymous sources and did not say which investigation had been referred to the Justice Department.

Representatives of the inspector general's office and the Interior and Justice departments did not immediately respond to requests for comment.