WASHINGTON - Former US President Donald Trump claimed on Wednesday that when he was in the White House, his powers were so broad he could declassify virtually any document by simply "thinking about it".

That argument - which came as he defended his decision to retain government documents in his Florida home in an interview with Fox host Sean Hannity - underscored a widening gap between the former president and his lawyers.

By contrast, they have so far been unwilling to repeat Mr Trump's declassification claim in court, as they counter a federal investigation into his handling of government documents.

In the interview, the former president said: "Different people say different things but as I understand it, if you're the president of the United States, you can declassify just by saying it's declassified, even by thinking about it.

"Because you're sending it to Mar-a-Lago or wherever you're sending it. There doesn't have to be a process. There can be a process, but there doesn't have to be.

"You're the president - you make that decision."

In the interview, Mr Trump also said that the federal agents who raided his Florida home might have been looking for Hillary Clinton's emails, news media reported.

"Were they looking for the Hillary Clinton emails that were deleted, but they are around someplace?" he said. When Mr Hannity asked Mr Trump if he was saying he had the emails. "No," Mr Trump answered.

Over the past week, a federal appeals court in Atlanta - along with Mr Trump's choice for a special master to review the documents seized last month - undermined a bulwark of his effort to justify his actions: Both suggested that there was no evidence to support the assertion that Mr Trump had declassified everything - in writing, verbally or wordlessly - despite what the former president may have said on TV.

On Thursday, the special master, Judge Raymond Dearie, also appeared to take aim at another one of Mr Trump's excuses - that federal agents had planted some of the records when they searched his Mar-a-Lago estate. In an order issued after the appellate court had ruled, Judge Dearie instructed Mr Trump's lawyers to let him know if there were any discrepancies between the documents that were kept at Mar-a-Lago and those that the FBI said it had hauled away.

By the time the Hannity interview aired late Wednesday, a three-judge appellate panel of the 11th US Circuit Court of Appeals - which included two jurists appointed by Mr Trump - had blocked part of a lower court order favourable to the former president. The panel brushed aside the suggestion that he had declassified 100 highly sensitive documents found in his residential and storage areas as both unfounded and irrelevant.

The court wrote that there was "no evidence that any of these records were declassified" and took note of the fact that, when Mr Trump's lawyers appeared before Judge Dearie this week, they too "resisted providing any evidence that he had declassified any of these documents".

The appellate panel went on to declare that the declassification issue, which Mr Trump has repeatedly thrust at the centre of the case, was "a red herring" that would not have factored into its ruling even if it had been extensively argued before them. Even if Mr Trump had, in fact declassified the records, the judges wrote, he was still bound by federal law, including the Presidential Records Act, that required him to return all government documents, classified or unclassified, when he left office.

Declassifying an official document would not alone "render it personal" or turn it into a possession he could hold onto after leaving office, the court said.

The judges in Atlanta were not alone in their opinion.

One day earlier, Judge Dearie expressed a similar form of scepticism. He pointedly told Mr Trump's legal team that since the classified documents were clearly marked classified, he intended to consider them as classified - unless they offered evidence to the contrary.

Wednesday's ruling was a major victory for the Justice Department, which argued that the earlier decision by Judge Aileen Cannon, whom Mr Trump appointed to the US District Court for the Southern District of Florida, had hamstrung its investigation and hampered the intelligence community's ability to conduct a separate intelligence assessment.

On Thursday, Judge Cannon modified her order for the special master review to exclude documents marked as classified, in line with the appeals court decision.

Nonetheless, the order seemed to raise new questions. Judge Cannon did not issue a written opinion explaining why she had taken that step before Mr Trump indicated whether he would appeal to the Supreme Court. By preemptively removing the portions of the order that the appeals court had blocked, she may have rendered any further litigation over the matter moot. Mr Trump's lawyers did not respond to requests for comment.

Shortly after Judge Cannon's order was issued, Judge Dearie released his own scheduling order for the review that will now be focused only on the roughly 11,000 documents that are not marked as classified.

Under his plan, the two sides would identify any disputes over whether the records are government or personal property, or privileged or unprivileged, by Oct 21.

After Judge Cannon rules on the disputed files, Judge Dearie said, he will entertain a motion, should Mr Trump wish to file one, to get back the seized items. Judge Dearie also said he would not seek any compensation since he is still actively hearing cases, but would hire a retired magistrate judge from the Eastern District of New York, James Orenstein, to assist him at a rate of US$500 per hour.

Mr Trump will still have to foot the bill, as specified in a previous ruling by Judge Cannon.

Mr Trump's legal team has merely hinted at the possibility that he declassified the documents, without taking a firm position in court, where making a false statement can have professional consequences.

In a letter to the Justice Department in May, Mr Trump's legal team first put forward a coy insinuation that Mr Trump might have declassified everything - while stopping short of actually saying he did so. At the time, Mr Trump had just received a grand jury subpoena for any sensitive records that remained at Mar-a-Lago, and the letter argued that Trump could not be charged under a law that criminalises mishandling classified information.

Even then, there were indications that the classification debate, while foremost in the former president's mind, was of limited use for his lawyers.

No credible evidence has emerged to support Mr Trump's claims, but even if they turned out to be true, legal experts say that would not get him out of legal trouble. NYTIMES