HARRISBURG — The FBI has begun a corruption investigation into how Gov. Tom Wolf’s administration came to issue permits for construction on a multibillion-dollar pipeline project to carry highly volatile natural gas liquids across Pennsylvania, The Associated Press has learned.

FBI agents have interviewed current or former state employees in recent weeks about the Mariner East project and the construction permits, according to three people who have direct knowledge of the agents’ line of questioning. All three spoke on condition of anonymity because they could not speak publicly about the investigation.