Former US president Donald Trump has claimed the FBI "raided" his Mar-a-Lago estate in Florida, which sources say is part of an investigation into whether he took classified records from the White House to his residence.

Disclosing the search in a lengthy statement, Mr Trump said that agents opened up a safe at his home and described their work as an “unannounced raid” that he likened to “prosecutorial misconduct”.

The search intensifies the months-long probe into how classified documents ended up in more than a dozen boxes located at Mar-a-Lago earlier this year.

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Mr Trump and his allies sought to cast the search as a weaponisation of the criminal justice system and a Democratic-driven effort to keep him from winning another term in 2024 — even though the Biden White House said it had no prior knowledge of it.

The Argus: Donald Trump likened the FBI's activity to "prosecutorial misconduct" (PA)Donald Trump likened the FBI's activity to "prosecutorial misconduct" (PA)

The current FBI director, Christopher Wray, was also appointed by Mr Trump five years ago and served as a high-ranking official in a Republican-led Justice Department.

Mr Trump wrote in a statement: “These are dark times for our nation, as my beautiful home, Mar-A-Lago in Palm Beach, Florida, is currently under siege, raided, and occupied by a large group of FBI agents.

“Nothing like this has ever happened to a President of the United States before.”

“After working and cooperating with the relevant Government agencies, this unannounced raid on my home was not necessary or appropriate."

Justice Department spokesperson Dena Iverson declined to comment on the search, including about whether Attorney General Merrick Garland had personally authorised it.

Mr Trump did not elaborate on the basis for the search but the Justice Department has been investigating the potential mishandling of classified information after the National Archives and Records Administration said it had retrieved from Mar-a-Lago 15 boxes of records containing classified information earlier this year.

The National Archives said Mr Trump should have turned over that material upon leaving office and it asked the Justice Department to investigate.

There are multiple federal laws governing the handling of classified records and sensitive government documents, including statutes that make it a crime to remove such material and retain it at an unauthorised location.

Though a search warrant does not suggest that criminal charges are near or even expected, federal officials looking to obtain one must first demonstrate to a judge that they have probable cause that a crime occurred.

Two people familiar with the matter, who spoke on condition of anonymity, said the search happened earlier on Monday and was related to the records probe. Agents were also looking to see if Mr Trump had additional presidential records or any classified documents at the estate.

Mr Trump has previously maintained that presidential records were turned over “in an ordinary and routine process”.