Hillary Clinton exchanged nearly two-dozen top secret emails from her unsecured, private server with three senior aides, the US State Department revealed in documents released to VICE News late Friday.

In the 22 emails, which were sent and received by Clinton in 2011 and 2012 while she was secretary of state, she discussed classified information with her deputy chief of staff, Jacob Sullivan, her chief of staff, Cheryl Mills, and Deputy Secretary of State William Burns. A majority of the top secret emails are email chains between Sullivan and Clinton.

This is the first time the State Department has revealed the identities of the officials who exchanged classified information with Clinton through her private email server.

One of the top secret emails from 2012 was described by the State Department as an "email chain originating with email from a State Department official to multiple State Department officials, concluding with message to Jacob Sullivan from Secretary Clinton." Another from the same year was an "email from a State Department official to multiple State Department officials, forwarded by Jacob Sullivan to Secretary Clinton and Cheryl Mills." Only one classified email was exchanged with Burns. State described that one as an "email from a State Department official to multiple State Department officials, forwarded by Jacob Sullivan to Secretary Clinton, Cheryl Mills, and William Bums."

The new disclosure by the State Department came three days before the Democratic National Convention kicks off in Philadelphia, where Clinton will formally accept her party's nomination for president, and minutes before Clinton announced her vice presidential pick, Senator Tim Kaine of Virginia.

In January 2015, VICE News filed a Freedom of Information Act (FOIA) lawsuit demanding that the State Department release all of the emails Hillary Clinton sent and received during her tenure as secretary of state. As a result, the government released 30,000 emails — but it also withheld 22 because they contained top secret information.

The seven email chains, the State Department said, would cause "exceptionally grave damage" to national security if publicly released. The new details released on Friday about the top secret emails was made in a so-called Vaughn Index, a document prepared in FOIA lawsuits in which government agencies justify the withholding of information under a FOIA exemption.

But unlike Vaughn Indexes that other government agencies produce in FOIA cases, which often contain detailed information about the subject matter of the withheld material, such as weapons programs or troop movements, the State Department did not provide detailed information in the index it turned over to VICE News because it considers the topics discussed to be top secret as well. State wouldn't even say what month the top secret emails were sent and received because that too is top secret. Instead, the State Department's Vaughn Index states reveals only who the authors and recipients of the communications were: Clinton, Sullivan, Mills, and Burns.

The index was promptly criticized as being insufficient by Steven Aftergood, the director of the Project on Government Secrecy at the Federation of American Scientists.

"State's document does not fulfill the requirements for a Vaughn Index," Aftergood said, citing government rules that say the indexes must provide ample justification on the withheld materials. "State did not 'identify each document' in such a way as to clearly distinguish among the various documents, and it certainly did not explain the damage that would result from disclosure of any or all of the documents. So it doesn't seem to meet the legal standard for a Vaughn index."

News reports published over the past six months, citing anonymous government officials, suggested the top secret emails referred to covert CIA drone strikes in Pakistan. Other reports said the emails may have identified CIA operatives who were working undercover.

In a letter sent to the heads of congressional oversight committees on January 14, Charles McCullough, the intelligence community's inspector general, said he received two sworn declarations from Intelligence Community members who determined that Clinton's communications contained information deemed to be "CONFIDENTIAL, SECRET, and TOP SECRET/SAP."

Top Secret/SAP, or special access program, is a classified designation "deemed so sensitive that it requires more rigorous protection than other classified information. Such protection may include heightened 'need to know' requirements, cover measures, and other steps," Aftergood added.

At the time of the disclosure, Brian Fallon, the press secretary for Clinton's presidential campaign, excoriated the finding.

"We firmly oppose the complete blocking of the release of these emails," Fallon said in a lengthy statement last January. "In at least one case, the emails appear to involve information from a published news article. This appears to be over-classification run amok. We will pursue all appropriate avenues to see that her emails are released in a manner consistent with her call last year."

Fallon did not respond to a request for comment about the new information in the Vaughn index on the top secret emails.

Clinton's email practices have taken a notable toll on her campaign and her trustworthiness in the eyes of voters. According to a recent poll, more than half of Americans think she broke the law by exclusively using private email and a private server to conduct official business during her tenure as secretary of state.

For more than a year, Clinton has insisted she never sent or received any emails from her private server that contained classified information. But earlier this month, FBI Director James Comey announced during a news conference that Clinton did send and receive classified information and — given her position as the nation's top diplomat — she should have known better.

"Seven e-mail chains concern matters that were classified at the Top Secret/Special Access Program level when they were sent and received," Comey said. "These chains involved Secretary Clinton both sending e-mails about those matters and receiving e-mails from others about the same matters. There is evidence to support a conclusion that any reasonable person in Secretary Clinton's position, or in the position of those government employees with whom she was corresponding about these matters, should have known that an unclassified system was no place for that conversation."

The FBI spent a year probing Clinton's use of a private email server and recommended to the Department of Justice that neither Clinton nor any of her aides should face charges for disseminating classified information over her private email server.

"Although we did not find clear evidence that Secretary Clinton or her colleagues intended to violate laws governing the handling of the classified information, there is evidence that they were extremely careless in their handling of very sensitive, highly classified information," Comey said.

Two days after Comey's press conference, the State Department said it would reopen an internal review into any mishandling of classified information in emails by Clinton and her top aides. Even though Clinton and her aides no longer work at the State Department, they could still be subject to a number of penalties, such as losing their security clearances.

Separately, in court documents submitted Friday in a separate FOIA lawsuit VICE News filed against the FBI seeking the contents of Clinton's email server, the FBI said it had started the process of turning over "thousands of documents" FBI agents retrieved from Clinton's private server that her aides had failed to turn over to the State Department. The FBI said it will continue to "transfer the retrieved materials to the State Department on a rolling basis... for review and determination as to whether they constitute agency records of the State Department under the Federal Records Act" and are subject to the FOIA.

"At this time, [the FBI] is unable to provide the Court with a date by which the FBI will transfer all of the retrieved materials to the State Department, or information regarding the precise volume of retrieved materials that will be transferred," government attorneys said in a status report filed in US District Court in Washington, DC. The FBI "expects to be able to provide the Court with more information regarding the time line for the completion of the transfer of the retrieved materials, and the approximate volume of materials, in the coming weeks."

Additionally, the FBI said it intends to release to VICE News on August 5 two letters the FBI sent to the State Department about its investigation into Hillary Clinton's email server and is "evaluating" whether it can also release secret declarations the bureau's FOIA chief filed earlier this year with the federal judge presiding over our case describing how the public release of any documents would have harmed the FBI's investigation while it was still ongoing.

This report has been updated.