PHILADELPHIA — Even as she contends with state criminal charges, Pennsylvania Attorney General Kathleen G. Kane is also facing scrutiny by the FBI, The Philadelphia Inquirer has learned.

In recent months, agents have questioned at least three people about several issues, including Kane’s role in negotiating a new contract with the union representing narcotics agents in her office, according to people familiar with the matter.

The agents sought information about whether Kane suggested to union officials she would look favorably on their contract if they supported her beleaguered chief of staff, sources said.

Investigators have also sought information about a trip Kane and several aides took to Haiti last year, and how it was paid for, according to the sources.

The scope and intensity of the federal inquiry are unclear, but it comes as Kane prepares to mount a legal fight against criminal charges she leaked confidential material to embarrass a critic and then lied about it under oath. A preliminary hearing in the case is scheduled for Monday.

A spokesman for the FBI in Philadelphia declined to comment Wednesday.

Kane’s lawyer, Gerald Shargel, could not be reached for comment.

Her spokesman, Chuck Ardo, said the office was unaware of a federal inquiry.

He said he had no knowledge of Kane’s discussions with Lodge 74 of the Fraternal Order of Police, which represents about 100 narcotics agents in the Attorney General’s Office.

Sources familiar with Kane’s negotiations with the union said they occurred in April, shortly after she promoted Jonathan Duecker to be her chief of staff.

Duecker was a controversial selection. Almost immediately, reports surfaced two women in the Attorney General’s Office — a narcotics agent and a prosecutor — had told their supervisors Duecker had made unwanted sexual advances to them. As The Inquirer has reported, Kane knew about the allegations before promoting him to the top post.