Attorneys for former National Security Adviser Michael Flynn said Thursday they’ve uncovered serious problems with his case, escalating their growing tension with federal prosecutors.

“While new counsel for Mr. Flynn has barely scratched the surface, counsel has identified crucial and troubling issues that should concern any court,” his attorneys wrote in a 13-page court filing.

The attorneys made the claim to the federal judge overseeing Flynn’s sentencing for lying to investigators about his communications with a former Russian ambassador.

Flynn’s attorneys did not hint at what the problems could be, saying his cooperation with federal prosecutors has hindered their investigation.

“We are not yet near a position to brief the court on the significant issues we are uncovering because we have spent virtually all of our time and effort cooperating,” they wrote in the filing.

Earlier this week, prosecutors dropped Flynn as a key witness in his former business partner’s criminal trial next week.

But his lawyers charge the status change should not impact his sentencing. Last year, special counsel Robert Mueller recommended that Flynn should receive little or no jail time because of his cooperation.

“There should be no negative change in Mr. Flynn’s status before this court because of anything in the [Eastern District of Virginia],” his legal team wrote.

The former business partner, Bijan Kian, has been indicted for failing to register as a foreign agent on behalf of the Turkish government.

Flynn was supposed to a crucial witness in the case against Mr. Kian, whose charges stem from his time with Flynn’s lobbying firm.

But court documents filed earlier this week suggested federal prosecutors have doubts about Flynn’s assertions regarding Mr. Kian.

His attorneys pushed back, accusing prosecutors of “retaliation,” because Flynn’s version of events did not reflect what they wanted to hear.

“Regardless of who might call Mr. Flynn as a witness, his testimony remains consistent with his grand jury testimony — which the government used to obtain the [Kian] indictment,” they wrote. “Furthermore the government as already acknowledged Mr. Flynn’s substantial assistance.”

Earlier Thursday, one of Flynn’s attorneys, Sydney Powell, appeared on Capitol Hill, where she spoke with The Washington Times.

She said that Flynn is continuing to cooperate with the government.

“We are doing everything we possibly can,” she told The Times.

She also said she didn’t know if the developments in the Kian case would impact the government’s earlier recommendation that he doesn’t face prison time.

“That’s purely up to the Department of Justice and what stance they want to take,” Powell said. “Our position is that he is continuing to cooperate. We have done everything humanly possible to do so. And we’re going to continue to do that.”

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