Presumptive Democratic nominee Hillary Clinton met with FBI officials Saturday about her private email server that has sparked a federal investigation, her campaign said.

"Secretary Clinton gave a voluntary interview this morning about her email arrangements while she was Secretary," Clinton campaign spokesman Nick Merrill said in an email Saturday afternoon. "She is pleased to have had the opportunity to assist the Department of Justice in bringing this review to a conclusion. Out of respect for the investigative process, she will not comment further on her interview."

Sources confirm to CBS News that the investigation is in its final phase and interviewing Clinton was one of the last steps before concluding the investigation and submitting recommendations on whether charges should be filed.

The meeting, which lasted approximately three-and-a-half hours, took place at FBI headquarters in Washington, D.C., according to a campaign aide.

Federal investigators have already interviewed close aides to the former secretary of state, including Huma Abedin, who faced questioning in April at the FBI's Washington field office.

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In May, Clinton told CBS News that she expected a quick conclusion to the FBI probe into whether she mishandled classified information on her server, which Clinton used exclusively to send and receive State Department correspondence.

"I always took classified material seriously," she told "Face the Nation" host John Dickerson. "There was never any material marked classified that was sent or received by me. And I look forward to this being wrapped up."

The news comes just as increased scrutiny has been turned on the Justice Department, which oversees the FBI, and Attorney General Loretta Lynch after the nation's top law enforcement officer had a spontaneous half-hour-long meeting with former President Clinton earlier this week.

In an interview at the Aspen Ideas Festival Friday, the attorney general said of the meeting with Clinton that she "certainly wouldn't do it again."

"Because I think it has cast a shadow over what it should not - over what it will not touch," Lynch said.

Ex-President Clinton seemed to express similar sentiments about the issue, according to one aide, who said the conversation with Lynch was "unplanned" and "entirely social in nature." The aide said that in light of how others could view the meeting, Clinton "agrees with the Attorney General that he would not do it again."

The current presumptive nominee also weighed in on the meeting Saturday, telling MSNBC in an interview that "hindsight is 20/20."

"Both the attorney general and my husband have said they wouldn't do it again even though it was from all accounts that I have heard and seen an exchange of pleasantries," Clinton said. "Obviously, no one wants to see any untoward conclusions drawn."

Lynch confirmed Friday that she would be accepting the recommendations of the career prosecutors in the email case, though the attorney general stopped short of formally recusing herself from the matter.

After Clinton's interview with the FBI, some Republicans were quick to criticize the latest developments, including general election rival Donald Trump.

"It is impossible for the FBI not to recommend criminal charges," Trump said in a tweet Saturday afternoon.

It is impossible for the FBI not to recommend criminal charges against Hillary Clinton. What she did was wrong! What Bill did was stupid! — Donald J. Trump (@realDonaldTrump) July 2, 2016

Republican National Committee chair Reince Preibus went on a tweet storm later in the day, panning Clinton and the Justice Department:

Hillary Clinton is the first major party presidential candidate to be interviewed by the FBI as part of a criminal investigation — Reince Priebus (@Reince) July 2, 2016

That FBI wanted her for ?ing reinforces her role in creating a culture which put her ambitions above State Dept rules & jeopardized natl sec — Reince Priebus (@Reince) July 2, 2016

And the American people need to have confidence that the Obama Justice Dept is conducting a fair & impartial investigation — Reince Priebus (@Reince) July 2, 2016

CBS News justice reporter Paula Reid contributed to this report.