Former US President Donald Trump has been implicated by one of his employees in a classified documents case, according to a court filing.

Yuscil Taveras, an IT director identified as Trump Employee 4 in legal documents, changed his testimony after switching lawyers, say prosecutors.

He now accuses Mr. Trump and two aides of “efforts to delete security camera footage”, says the filing.

The 77-year-old ex-president faces 40 charges in the case.

Mr. Trump, his close personal aide Walt Nauta and Mar-a-Lago maintenance worker Carlos De Oliveira have all pleaded not guilty.

The former president is accused of mishandling the storage of sensitive files at his Florida home, Mar-a-Lago, and trying to cover up the alleged crime by deleting security footage.

The court document filed on Tuesday says Mr. Taveras changed lawyers after special counsel Jack Smith, who is overseeing the case, notified him he was being investigated for perjury.

His former attorney also represents Mr. Trump's co-defendant Mr Nauta.

During grand jury testimony in March this year, Mr. Taveras “repeatedly denied or claimed not to recall any contacts or conversations about the security footage at Mar-a-Lago”.

Prosecutors said they obtained evidence that Mr. De Oliveira had asked Mr. Taveras to delete the CCTV footage after investigators demanded the video as they tracked the movement of boxes containing the documents inside the resort.

The chief judge overseeing the federal grand jury, James Boasberg, offered a public defender to Mr. Taveras after prosecutors pointed out a conflict of interest for his lawyer Stanley Woodward, who was being partly funded by Mr. Trump's Save America political action committee.

“Advising Trump Employee 4 to correct his sworn testimony would result in testimony incriminating Mr Woodward's other client, Nauta; but permitting Trump Employee 4's false testimony to stand uncorrected would leave Trump Employee 4 exposed to criminal charges for perjury,” the filing said.

On 5 July, Mr. Taveras informed Judge Boasberg that he no longer wished to be represented by Mr. Woodward and would instead accept the offer of legal aid.

“Immediately after receiving new counsel, Trump Employee 4 retracted his prior false testimony and provided information that implicated Nauta, [Carlos] De Oliveira, and Trump in efforts to delete security camera footage, as set forth in the superseding indictment,” the court filing says.

Mr .Taveras is not charged in the case, which is scheduled for trial next May.

Mr. Trump is fighting criminal charges in three other cases. (BBC)