Federal prosecutors Friday rejected former national security adviser Michael Flynn's suggestion that he should have been warned of the consequences of lying to the FBI, telling a judge that Flynn's false statements were "voluntary and intentional."

In a memo to the court, prosecutors from special counsel Robert Mueller's office said there was no basis for Flynn's implication that he was coerced into lying when he spoke to the FBI on Jan. 24, 2017.

"The interview was voluntary, and lacked any indicia of coercion," the memo says. Flynn was "relaxed and jocular" during the interview session, it adds.

Prosecutors said in the memo that the court should reject Flynn's attempts to downplay the seriousness of his offense but they stuck to the recommendation of a prison term on the low end of the sentencing guidelines, citing his "cooperation and military service."

Flynn pleaded guilty in December 2017 to a charge of lying to the FBI about his conversations with Russian ambassador Sergey Kislyak in the weeks before President Donald Trump took office. He faces up to six months in prison when he is sentenced on Dec. 18.

Mueller's office had previously told the court that he should receive little to no jail time due to his "substantial assistance" in the special counsel's Russia probe.

Flynn's team subsequently told the court that Flynn "saw the FBI agents as allies" when they interviewed him at the White House last year. Flynn's lawyers, citing internal FBI documents, noted that officials had made a decision for the agents not to warn their client that lying to the FBI was a crime.

In the memo filed Friday, the prosecutors said Flynn, given his extensive law enforcement experience, should have known better than to lie to federal investigators.

"A sitting National Security Advisor, former head of an intelligence agency, retired lieutenant general, and 33-year veteran of the armed forces knows he should not lie to federal agents," the memo says. "He does not need to be warned it is a crime to lie to federal agents to know the importance of telling them the truth."

Flynn's lawyers, Robert Kelner and Stephen Anthony, declined to comment.