The FBI has raided Donald Trump’s Mar-A-Lago, breaking into a safe and sparking a tirade from the former US president.

“My beautiful home Mar-A-Lago in Palm Beach, Florida, is currently under siege, raided and occupied by a large group of FBI agents,” Mr Trump said in a lengthy statement on Tuesday (Australian time) that included a link for donations to his political action committee.

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

“They even broke into my safe!”

A person familiar with the matter said the action was related to a probe into whether Mr Trump had taken classified records from his White House tenure to his Florida residence.

The search began early on Monday (local time), with agents focused on the area of the Palm Beach club where Mr Trump has his offices and personal quarters, a person familiar with the matter told CNN.

The FBI’s search included examining where documents were kept, according to another person familiar with the investigation, and boxes of items were taken. It followed the National Archives recovering boxes of classified White House records from Mar-A-Lago in recent months – with the raid apparently focused on whether anything had been left behind.

The action, which the FBI and Justice Department did not immediately confirm, marked a dramatic escalation in law enforcement scrutiny of Mr Trump and came as he continued to lay the groundwork to make another bid to be US president.

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

Mr Trump said the action represented “dark times for our nation” and compared it to Watergate.

“Here, in reverse, Democrats broke into the home of the 45th president of the United States,” he wrote.

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

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

Eric Trump, one of the former president’s adult children, told Fox News the search concerned boxes of documents that Mr Trump brought with him from the White House. He said his father had co-operated with the National Archives on the matter for months.

Federal law bars the removal of classified documents to unauthorised locations, though it is possible that Mr Trump could try to argue that, as president, he was the ultimate declassification authority.

There are multiple statutes governing classified information. They include a law punishable by up to five years in prison that makes it a crime to remove such records and retain them at an unauthorised location.

Another statute makes it a crime to mishandle classified records either intentionally or in a grossly negligent manner.

Mr Trump was not at Mar-A-Lago when the FBI arrived because he was in New York, Fox News Digital reported. It published a photo that a Fox reporter said showed him leaving Trump Tower.

Mr Trump, who has made his club in Palm Beach his home since leaving the White House in January 2021, has generally spent summers at his golf club in Bedminster, New Jersey, because Mar-A-Lago typically closes for the summer.

Any search of a private residence would have to be approved by a judge, after the investigating law-enforcement agency demonstrated probable cause that a search was justified.

Monday’s raid would almost certainly have also been approved by FBI Director Christopher Wray, a Trump appointee, and his boss, Mr  Garland, who was appointed by Mr Trump’s successor and political rival, President Joe Biden.

Democratic supporters of Mr Biden have criticised Mr Garland for being overly cautious in investigating Mr Trump over his attempts to overturn his 2020 election loss.

But Trump supporters in turn have accused the Democrats of weaponising the federal bureaucracy to target Mr Trump, even as Mr Biden has taken steps to distance himself from the Justice Department.

Republicans, including national committee chair Ronna McDaniel, House Minority Leader Kevin McCarthy and Florida Governor Ron DeSantis, denounced the search on Monday.

Mr McCarthy tweeted that the Justice Department “has reached an intolerable state of weaponised politicisation” and if Republicans won control of the US House, they would investigate the department.

The White House papers probe is hardly the only legal headache confronting the former president. A separate investigation related to efforts by Mr Trump and his allies to undo the results of the 2020 presidential election and the January 6, 2021, riot at the US Capitol has also been intensifying in Washington.

And a district attorney in Fulton County, Georgia, is investigating whether Mr Trump and his close associates sought to interfere in that state’s election, which was won by Democrat Joe Biden.

-with AAP