WASHINGTON (Reuters) - U.S. prosecutors have canceled plans to call President Donald Trump’s former national security adviser Michael Flynn as witness in a trial involving Flynn’s former business partner - an abrupt change that raises questions about Flynn’s cooperation with the government and its impact on his sentencing.

Former U.S. national security adviser Michael Flynn departs after his sentencing was delayed at U.S. District Court in Washington, U.S., December 18, 2018. REUTERS/Joshua Roberts

In court filings unsealed on Tuesday, federal prosecutors in Alexandria, Virginia, said they now planned to portray Flynn as a “co-conspirator” along with Bijan Rafiekian in a scheme to persuade U.S. politicians to support Turkey’s bid to extradite cleric Fethullah Gulen, a political adversary to the Turkish government who lives in the United States.

Flynn’s cooperation in Rafiekian’s trial in Virginia, which starts this month, could have an impact on how he is sentenced in his own case in a federal court in Washington.

Flynn was among the first people in Trump’s inner circle to be charged by Special Counsel Robert Mueller for lying to investigators about his December 2016 conversations with Sergei Kislyak, Russia’s then-ambassador in Washington, about U.S. sanctions imposed on Moscow by President Barack Obama.

Flynn later pleaded guilty to lying to investigators and agreed to cooperate in hopes of receiving a more lenient sentence.

As part of that plea agreement, he also admitted to submitting false statements to the government regarding his lobbying work with Rafiekian, also known as Bijan Kian, on behalf of Turkey.

Flynn’s new lawyers now say he did not knowingly submit anything false when retroactively registering under the Foreign Agents Registration Act (FARA) in early 2017.

“Undersigned counsel advised the prosecutors that Mr. Flynn did not know and did not authorize signing the FARA form believing there was anything wrong with it,” lawyers Jesse Binnall and Sidney Powell said in a court filing.

Flynn was due to be sentenced last December, but his sentence was delayed after U.S. District Judge Emmet Sullivan lambasted him at a contentious hearing in December in which the judge accused Flynn of selling out his country.

Sullivan gave him the option to delay his sentence until his cooperation with the government was complete.

Last month, Flynn dismissed his lawyers for unknown reasons and hired Powell, an attorney who frequently appears on Fox News and has been critical of Mueller’s investigation.

Flynn has also opposed the government’s decision to designate him as an unindicted co-conspirator in the Virginia trial, saying that contradicts claims the government previously made.

“The government’s sudden decision to reverse its long-stated position that Mr. Flynn is its cooperating witness, and to turn him into an unindicted co-conspirator, is extremely prejudicial to Mr. Flynn,” his attorneys wrote in a court filing on Monday.

In a statement, Powell said her client was still cooperating with the government even if he is not called as a witness.

Later on Tuesday, Sullivan issued an order telling prosecutors to file a brief with the court by 5 p.m. on Wednesday explaining how their reversal would affect Flynn’s case in Washington.