A federal judge ordered the release of audio of a voicemail former Trump lawyer John Dowd left for retired Lt. Gen. Michael Flynn's lawyer in the middle of special counsel Robert Mueller's Russia investigation.

In a brief court filing Thursday, U.S. District Judge Emmet Sullivan instructed the court clerk to put the audio version of the Nov. 22, 2017 voicemail left for Robert Kelner on the public docket.

The order comes less than a week after the transcript of the voicemail was released, per Sullivan's order.

Mueller referenced parts of the voicemail in his final report, showing how Dowd asked for a "heads up" if Flynn knew information that "implicates" Trump after Flynn dropped from a joint defense agreement with the president.

Defenders of the president, including Rep. Devin Nunes, R-Calif., have highlighted how parts of the transcript were left out and have raised concerns about a possible smear job.

In an interview on Fox News this week, Dowd said "by taking out half my words," they changed the "tenor and the contents" of his conversation with Flynn's lawyer.

"We also know this entire report by Mueller is a fraud. And we're going to find more of these things," said Dowd, who resigned as Trump's lead counsel for the Mueller investigation in March 2018.

Sullivan's order Thursday came just hours after Flynn fired his attorneys, including Kelner, ahead of the sentencing in his criminal case.