Hillary Clinton's campaign is questioning a report about a top aide to Clinton when she was secretary of state also conducting interviews for the Clinton Foundation, saying implications about a potential conflict of interest are “absurd.”

Then-Chief of Staff Cheryl Mills took an Amtrak train from Washington to New York City in June 2012 to interview two executives to potentially become the foundation’s next leader, sources told CNN, which first reported the story.

Clinton purportedly accepted the secretary of state post in 2009 in part on the condition that any foundation activity would neither “create conflicts nor the appearance of conflicts” of interest for her.

The CNN report doesn’t state Mills broke any rules but suggested her interviewing trip has added to the “blurred lines” between Clinton’s government work and non-government activities, which have long created problems for her and husband President Bill Clinton.

Hillary Clinton’s use of a private server as secretary of state to send and receive official emails has also added to that perception.

The Clinton campaign said Friday that Mills “volunteered her personal time” and paid for her own travel to New York City.

“And it was crystal clear to all involved that this had nothing to do with her official duties,” the campaign said. “The idea that this poses a conflict of interest is absurd."

Mills' attorney also purportedly said such work was voluntary.

The foundation did not immediately respond to a FoxNews.com request Saturday for comment.

The CNN report comes the same week as a new batch of Clinton emails seemed to show foundation donors got preferential treatment during Clinton’s tenure at the State Department.

Conservative watchdog Judicial Watch released the 44 new email exchanges, which the group says were not in the original 30,000 handed over to the State Department. Clinton has repeatedly claimed she turned over all work-related emails during the now-closed probe into her private server use.

The documents challenge Clinton's insistence that there was "no connection" between the foundation and her work at the State Department.

In one email exchange, Doug Band, an executive at the Clinton Foundation, tried to put billionaire donor Gilbert Chagoury -- a convicted money launderer -- in touch with the U.S. ambassador to Lebanon because of the donor’s interests there.

And a report this week by The Daily Caller says that several investigations are being launched, including one led by U.S. Attorney Preet Bharara of the Civil Frauds Unit that will focus on the foundation's dealings in New York. The agency has declined to comment.

The Senate Judiciary Committee, led by Sen. Chuck Grassley, R-Iowa, has also tried to get answers about Mills' New York trip. Grassley sent Secretary of State John Kerry a letter in January about the issue.