President Obama is believed to have used a pseudonym in email exchanges with Hillary Clinton when she worked at the State Department, according to a new batch of documents released Friday by the Federal Bureau of Investigation.

The same notes also showed Clinton's State Department team notified the White House immediately after the former secretary of state updated her primary email address to a private one.

The documents released Friday included notes from interviews with some of Clinton's closest aides, including longtime confidante Huma Abedin.

Buried deep in the more than 180 pages released by the federal agency are the following notes from an interview conducted on April 5, 2015:

Abedin provided that when Clinton needed to contact the president she would have [REDACTED] call the Oval Office to coordinate the meeting or call. Abedin believed that Clinton had the president's email address but Abedin did not know what it was. Abedin noted that the president could only receive from approved addresses. She recounted that when Clinton changed her primary email address they had to notify the White House so that Clinton's would not be rejected by the server. Abedin was not sure how often Clinton emailed the president. Abedin was shown an email chain dated June 28, 2012, with the subject "Re: Congratulations!" Abedin did not recognize the name of the sender. Once informed that the name is believed to be a pseudonym used by the president, Abedin exclaimed, "How is this not classified?" Abedin then expressed her amazement at the president's use of a pseudonym and asked if she could have a copy of the email.

Clinton, who is now the Democratic nominee, never once used an official email address during her entire tenure at the State Department.

The latest revelation from the FBI's official investigation of Clinton's unauthorized homebrew server comes months after Obama's claimed repeatedly in 2015 that he didn't know about her private email setup until it was on the news.

"My emails, the Blackberry I carry around, all those records are available and archived," the president said in an interview in March with CBS News' Bill Plante. "I'm glad that Hillary's instructed that those emails about official business need to be disclosed."

Asked when he learned of Clinton's private emails, Obama responded unequivocally, "the same time that everybody else learned it through news reports."

Later, in October of that same year, Obama repeated in an interview on "60 Minutes" that he was did not know about Clinton's private email.

"Did you know you about Hillary Clinton's use of a private email server –" CBS' Steve Kroft began.

"No," Obama stated flatly.

"—while she was secretary of state?" Kroft finished.

The president repeated, "No."

The president and his administration have yet to explain why he allegedly used a pseudonym in email exchanges with Clinton, who reportedly used only personal addresses for electronic communications

The State Department claimed in January that Clinton exchanged approximately 18 emails with Obama. The State Department also explained that it would not release the emails because they allegedly contain "a category of top secret information."

"I can confirm that 18 emails comprised of eight distinct email chains between former Secretary Clinton and President Obama are being withheld in full from the State Department's FOIA production today of these emails of Secretary–former Secretary Clinton's emails," State Department Spokesman John Kirby told reporters.

Later, in March, Earnest told reporters that Obama's email exchanges with Clinton did not contradict the president's earlier claim he new nothing of her private server setup.

"[T]he point that the President was making is not that he didn't know Secretary Clinton's email address – he did – but he was not aware of the details of how that email address and that server had been set up or how Secretary Clinton and her team were planning to comply with the Federal Records Act," the White House press secretary said.

He added, "the point is the president did email with Secretary Clinton. I assume that he recognized the email address that he was emailing back to. But, again, the question here is about compliance with the Federal Records Act. And understandably, the kinds of things that a President and his Secretary of State talk about are pretty weighty, national issues."

In September, the State Department produced an index describing the subject matter of the 18 supposedly classified emails. The exchanges, according to State, were mostly notes of congratulation and various pleasantries.

State Department lawyers continue to block Freedom of Information Act requests for the release of email exchanges between Clinton and Obama, citing "presidential communications privilege."

The White House contacted the Washington Examiner to note Earnest's concession in March that the president clearly knew of Clinton's private email addresses. A White House spokesperson did not respond for further comment when asked to explain why the president allegedly used a pseudonym.

This article has been updated to include remarks from a March 3, 2015, White House press briefing. The headline has also been amended.