A top State Department official offered a “quid pro quo” to an FBI investigator to declassify an e-mail from Hillary Clinton’s private server in exchange for allowing the bureau to operate in countries where it was banned, stunning new documents revealed Monday.

The FBI documents show that Undersecretary of State Patrick Kennedy pitched the deal to the unnamed agent, allegedly as part of an effort to back up Clinton’s claim that she did not send or receive classified documents on the server in her Westchester home.

“[Redacted] indicated he had been contacted by [Kennedy], Undersecretary of State, who had asked his assistance in altering the e-mail’s classification in exchange for a ‘quid pro quo,’ ” according to the documents, which summarized interviews the feds conducted in the summer of 2015 while investigating Clinton’s e-mail practices.

“[Redacted] advised that in exchange for marking the e-mail unclassified, STATE would reciprocate by allowing the FBI to place more Agents in countries where they are presently forbidden,” the document added.

One State Department staffer described feeling “immense pressure” to complete the review quickly and to not label anything as classified.

Officials were told there was nothing classified in the 296 emails about Benghazi that were among those under review, the document stated.

State’s inspector general also told the FBI that Kennedy’s “tone and tenor were definitely not positive when dealing” with his office.

“[REDACTED] believes STATE has an agenda which involves minimizing the classified nature of the CLINTON e-mails in order to protect STATE interests and those of CLINTON,” the documents stated.

The documents also showed that Kennedy was not happy cooperating with the feds — and wanted some emails kept secret.

In one instance, Kennedy wanted information changed to an obscure classification code called B9, to “allow him to archive the document in the basement of DoS [Department of State] never to be seen again.”

The B9 exemption is normally used to protect geological and geophysical data and maps to keep details about oil and gas wells secret.

Some of the interview notes appear contradictory.

In one, an FBI official said he heard that State had offered the “quid pro quo.”

But a different FBI official in a separate document said it was the FBI that made the offer to review the e-mail if State helped the bureau get agents in Iraq.

In what could be a scene out of a novel, a group of ranking State officials — dubbed “the shadow government” — would meet on Wednesdays to discuss the Clinton e-mail scandal, the documents showed.

During another meeting with the FBI, CIA and other agencies, Kennedy was asked whether any of the emails in question were classified.

“Making eye contact with [redacted] KENNEDY remarked, ‘Well, we’ll see,’” Kennedy responded.

Donald Trump’s campaign didn’t waste any time attacking the latest disclosures.

“CORRUPTION CONFIRMED: FBI confirms State Dept. offered ‘quid pro quo’ to cover up classified emails,” Trump said on Twitter, retweeting a post by Official Team Trump.

“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 e-mails shows a cavalier attitude towards protecting our nation’s secrets. Kennedy must resign from the State Department immediately,” said Trump spokesman Jason Miller.

House Oversight Committee Chair Jason Chaffetz (R-Utah)and House Intelligence Committee Chair Devin Nunes (R-Calif.) wrote to Secretary of State John Kerry demanding that Kennedy be fired and an investigation started.

“We find Under Secretary Kennedy’s actions extremely disturbing. Those who receive classified intelligence should not barter in it – that is reckless behavior with our nation’s secrets,” they said in a statement. “Someone who would try to get classification markings doctored should not continue serving in the State Department or retain access to classified information. Therefore, President Obama and Secretary Kerry should immediately remove Under Secretary Kennedy pending a full investigation.”

Both State and the FBI said Monday that the document under discussion remained classified and that the request for agents to operate in other countries was not part of any quid pro quo deal.

The bureau said in a statement that investigators were reviewing the emails to determine whether they were properly classified.

“Any assertion that this was somehow a tit for tat or quid pro quo or exchange in that manner, frankly, is insulting,” State spokesman Mark Toner told reporters.

“[The agent] was on the phone with Pat Kennedy and took advantage of that fact to raise the issue of [more] slots in Baghdad,” he said.

“I can’t speak to what his or her intentions were saying these kinds of things. Clearly he was expressing a personal opinion about what happened,” he added.

Clinton’s campaign manager, Robby Mook argued that disputes over classification between State and other departments was “not unusual.”

He called for an investigation into the FBI’s investigation.

The documents were released under the Freedom of Information Act following a lawsuit by the conservative watchdog group Judicial Watch.

We are disconcerted by what we have found thus far from publicly accessible sources about the possible hacking of Hillary Clinton’s illicit server,” Tom Fitton, the group’s president, said in a statement.

“It is unfortunate that Judicial Watch – not Congress or federal law enforcement – undertook this basic investigative step.”