The White House is attempting to block the release of emails between President Barack Obama and former Secretary of State Hillary Clinton, officials told the New York Times Friday.

The content of the emails remains unknown, but the White House insisted the decision to not release the messages was not based on their content, but rather "is intended to defend the principle that presidents must be free to receive advice from their advisers without fear that the conversations will be made public during their time in office," reported the Times.

"There is a long history of presidential records being kept confidential while the president is in office," said a White House official. "It is a principle that previous White Houses have vigorously defended as it goes to the core of the president's ability to receive unvarnished advice and counsel during his time in office and is central to the independent functioning of the Executive Branch."

The official said the emails will be released long after Obama leaves office, as required by law.

Nonetheless, the decision is likely to spark criticism from congressional Republicans who have pressed for the full disclosure of Clinton's State Department emails, and are concerned about her exclusive use of a private, unsecured home-based server during her tenure.

Officials told the Times that Obama does not plan to assert executive privilege over the correspondence, a legal authority presidents try to avoid invoking. Obama has used it only once before, to prevent a congressional subpoena of documents relating to operation Fast and Furious, in which U.S. agents sent weapons across the border and into the hands of Mexican drug cartels, reported Business Insider.

The State Department discovered the secret Obama emails as it was going through Clinton's messages to prepare them for public release. The messages were then sent to the White House for review.

Today, the State Department released about 7,000 more pages of Clinton's emails. More than half of the 55,000 total pages have now been made public. The latest release included 268 messages that have been classified since they were sent, bringing the total number of classified emails found on her server to 671, according to USA Today.

The FBI is currently conducting an investigation into whether Clinton mishandled classified information.