Former national security adviser Michael Flynn’s legal team charged in court Tuesday that the Department of Justice cleared Flynn of being a Russian agent in a memo as far back as January 2017 — but that prosecutors still haven't produced the document.

The claim came as Flynn's lawyers said in a status conference in a Washington, D.C., courthouse that they are now seeking to have the case against him thrown out, accusing the prosecution of "egregious conduct and suppression” of possibly exculpatory evidence.

“We've ... learned that there was a letter dated January 30th, 2017, or an internal memo from the Department of Justice, that completely exonerates Mr. Flynn of being an agent of Russia, and that document has not been produced to us yet," lawyer Sidney Powell said, according to a transcript of Tuesday's hearing obtained by Fox News.

FLYNN LEGAL TEAM ACCUSES PROSECUTORS OF MISCONDUCT

Powell continued: "So they had a lot of information that they didn't disclose. They also have knowledge of a letter from the British Embassy that completely discredits [Trump dossier author] Christopher Steele and undoes the whole Steele dossier debacle."

Fox News learned about the memo's existence last week. Asked by Fox News earlier this week if they were aware of the memo and could provide it, a DOJ official said they would try to identify it.

But responding to Powell's concerns in court on Tuesday, a government lawyer said they were irrelevant, noting they did not accuse Flynn of being a Russian agent in the first place, according to the transcript.

"The government has not alleged in any filings in this court or before the court that the defendant is an agent of Russia. That is not part of this case. That is not part of the act that he has pled guilty to. It was lying to the FBI about particular communications involving Russia, not being an agent of Russia," prosecutor Brandon Van Grack said.

As Van Grack noted, Flynn was charged – and dismissed from the Trump administration – for misleading statements about his conversations with then-Russian ambassador to the U.S. Sergey Kislyak.

But new developments raise questions over the underlying offense that formed the basis for the initial FBI and DOJ investigation into Flynn.

Aside from Powell's latest claims in court, Fox News reported on Monday that then-Deputy FBI Director Andrew McCabe told the White House in early February 2017 that the bureau was not considering Flynn for a potential Logan Act prosecution over contacts with the Russian ambassador before Donald Trump was sworn in as president. McCabe was referring to the rarely prosecuted 200-year-old statute that bars American citizens from engaging with a foreign government without authorization from the current U.S. government.

The records also indicated that Flynn reported, on two separate occasions, in the days leading up to his White House firing, that FBI agents told him the bureau investigation was over or being closed out.

Flynn was never charged with improperly communicating with Kislyak, but in December 2017 pleaded guilty to a single count of making false statements as part of a plea deal with prosecutors.

Powell remarked later on Tuesday at the hearing: "There never would have been a plea to begin with if the government had met its Brady obligation disclosing what it knew before Mr. Flynn entered a plea and, frankly, before he even made a proffer."

ANDY MCCARTHY: FLYNN SHOULDN'T HAVE BEEN PROSECUTED

The "Brady material" complaint is in reference to the Supreme Court case Brady v. Maryland, which established the government's obligation to turn over all exculpatory evidence. The accusation came as both sides have squabbled over a sentencing date.

Flynn's defense team also wants all the documents surrounding the FBI’s interview of Flynn. Prosecutors claim they already turned all those documents over to Flynn's team prior to the plea deal.

The government has "provided all drafts of that interview report of which it is in possession," prosecutors said Tuesday.

Powell also suggested there is another document that hasn't been released. "It would be in the FBI computer system," Powell said.

Powell additionally told the court there is evidence that Flynn passed a polygraph test. "There is just a plethora of information out there that we need the actual documents to support and the notes to support," she said.

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After months of delays, though, prosecutors have said they are ready to proceed to sentencing. On Tuesday, U.S. District Judge Emmet Sullivan indicated he would like to set a tentative sentencing date of Dec. 18.

"There is far more at stake here than sentencing," Powell said. "There were stunning failures to produce Brady material, going back to July of 2017."

Fox News' Catherine Herridge, Alex Pappas and Jake Gibson contributed to this report.