A US prosecutor has called on a judge to reconsider her dismissal of Alec Baldwin's involuntary manslaughter trial, disputing the court's ruling that law enforcement authorities deliberately withheld key evidence in their case against the Hollywood star.

In a court motion made public Wednesday, New Mexico prosecutor Kari Morrissey said the decision to throw out the trial over a fatal shooting on the movie set of "Rust" was flawed, and that the evidence was held back only because it was "immaterial."

"There was no cover-up because there was nothing to cover up," said the filing, which "respectfully requests the Court reconsider its dismissal of the case with prejudice."

Hollywood A-lister Baldwin was pointing a gun in the direction of cinematographer Halyna Hutchins during a rehearsal in October 2021 when the weapon fired, killing her and wounding the film's director.

Prosecutors claimed he ignored basic gun safety laws and acted recklessly on set.

The defense said the actor had no responsibility for checking the weapon's contents and did not know it contained live rounds.

The high-profile case went to trial in July, but collapsed in spectacular fashion as judge Mary Marlowe Sommer found important evidence had been withheld from the defense.

Live bullets potentially matching the round used in the fatal shooting had been handed to law enforcement by former police officer Troy Teske, it emerged during trial.

However, they were not disclosed to Baldwin's lawyers, and the evidence was not cataloged under the "Rust" case file by crime scene technicians.

Sommer ruled that the withholding of evidence was "intentional and deliberate." 

She swiftly dismissed the case against Baldwin, who could have been sentenced to 18 months in prison if found guilty.

Legal experts said Baldwin was highly unlikely to see the inside of a criminal court again over the shooting.

But in their new motion, prosecutors argue that the "buried" rounds could have been "purchased at any gun store two and a half years after Ms Hutchins death" and were "immaterial to the case against Mr. Baldwin."

"Nothing about the details of how the live rounds were introduced to the set is relevant or material to the charges against Mr. Baldwin... it was still Alec Baldwin's responsibility to handle his real prop gun safely," they wrote.

The motion also asks for Baldwin's lawyers to be ordered to explain how they learned of the ammunition handed to police by Teske, suggesting that "a record for possible review by a higher court can be created."