A top US State Department official allegedly "pressured" the FBI to downgrade the classification of a Hillary Clinton email, documents released on Monday (17 October) by the bureau show.

An unnamed FBI official told investigators Patrick Kennedy, under secretary of state for management, attempted in late June or early of July of 2015 to have the FBI change a classified email to unclassified. According to Reuters, the FBI official claimed the State Department's office of legal counsel had questioned the FBI's ruling that the information in the email was classified, but the FBI remained firm.

The official's colleague then received a call from Kennedy in which he "asked his assistance in altering the email's classification in exchange for a 'quid pro quo'." In exchange, Kennedy promised the State Department would allow the FBI to place agents in more countries, Politico reported.

The official went on to claim that he participated in at least two discussions in which Kennedy "continued to pressure" the FBI about the email. According to Reuters, the official claimed Kennedy appeared to be attempting to protect Clinton as the FBI and State are engaged in an interagency review of her emails being prepared for public release.

Kennedy followed up by asking during a private meeting if the FBI could "see their way to marking the email unclassified?" an unnamed official said. "According to [REDACTED], Kennedy spent the next 15 minutes debating the classification of the email and attempting to influence the FBI to change its markings."

According to Politico, Kennedy continued to pressure the bureau by reaching out to Michael Steinbach, the executive assistant director of the FBI's national security branch, but Steinbach refused to change the emails' classification.

In another interview, an FBI employee said that though Kennedy reached out about declassifying the email, it was the bureau that brought up getting agents in Iraq. The FBI employee said he spoke to Kennedy and suggested he would "look into the email matter" if Kennedy "would provide authority concerning the FBI's request to increase its personnel in Iraq".

The State Department deputy spokesperson Mark Toner denied any quid pro quo was offered. "This allegation is inaccurate and does not align with the facts," Toner said in a statement on Monday (17 October). "To be clear: the State Department did upgrade the document at the request of the FBI when we released it back in May 2015."

The FBI also denied that quid pro quo was offered in an attempt to have the emails' classification changed, CNN reported.

"The FBI determined that one such email was classified at the secret level," FBI said in a statement. "A senior State Department official requested the FBI re-review that email to determine whether it was in fact classified or whether it might be protected from release under a different FOIA exemption. A now-retired FBI official, who was not part of the subsequent Clinton investigation, told the State Department official that they would look into the matter. Having been previously unsuccessful in attempts to speak with the senior State official, during the same conversation, the FBI official asked the State Department official if they would address a pending, unaddressed FBI request for addition FBI employees assigned abroad."

The email remained classified and there was no increase in FBI employees in Iraq.

The campaign of Republican nominee Donald Trump released a statement from spokesman Jason Miller calling the documents "deeply disturbing". Miller said: "The news that top Clinton aide Patrick Kennedy tried to engage in a blatant quid pro quo for changing the classification level of several of Clinton's emails show a cavalier attitude towards protecting our nation's secrets."