The FBI searched the Maryland home and Washington office of former Trump administration national security advisor John Bolton as part of a criminal investigation into the potential mishandling of classified information, a source said.

Bolton, who emerged as an outspoken critic of US President Donald Trump after being fired in 2019 and fought with the first Trump administration over a scathing book he wrote documenting his time in the White House, was not in custody on Friday and has not been charged with any crimes, said the source.

The searches, seemingly the most significant public step the Justice Department has taken against a perceived enemy of the president, are likely to elicit fresh concerns that the Trump administration is using its law enforcement powers to target the Republican’s foes.

They come as the Trump administration has moved to examine the activities of other critics, including by authorising a grand jury investigation into the origins of the Trump-Russia probe that dogged Trump for much of his first term, and as FBI and Justice Department leaders signal their loyalty to the president.

Speaking during an unscheduled visit to the White House Historical Association, Trump said he had seen news coverage of Friday’s searches and expected to be briefed about it by the Justice Department but also insisted he didn’t “want to know about it”.

“I could know about it. I could be the one starting it. I’m actually the chief law enforcement officer. But I feel that it’s better this way,” Trump said.

Bolton had said in interviews this year that he was mindful that he could be scrutinised, having in January told reporters shortly before Trump took office, “Anybody who ever disagrees with Trump has to worry about retribution. It’s a pretty long list.”

An FBI search like the one at Bolton's properties requires authorisation from a federal magistrate judge. It wasn't immediately clear what information authorities submitted to demonstrate that they had probable cause of a crime, though the Justice Department years ago launched an investigation into whether Bolton improperly disclosed classified information in a book manuscript he had written. The inquiry was later closed.

Vice President JD Vance denied in an NBC News interview on Friday that Bolton was being targeted because of his criticism of Trump, “If there’s no crime here, we’re not going to prosecute it. If there is a crime here, of course, Ambassador Bolton will get his day in court. That’s how it should be.”

Bolton was in his office building at the time. The Justice Department had no comment, but leaders appeared to cryptically refer to the searches in a series of social media posts Friday morning.

FBI Director Kash Patel, who included Bolton on a list of “members of the Executive Branch Deep State” in a 2023 book he wrote, posted on X: “NO ONE is above the law… @FBI agents on mission.” Attorney General Pam Bondi shared his post, adding: “America’s safety isn’t negotiable. Justice will be pursued. Always.”

The Justice Department is separately conducting mortgage fraud investigations into Democratic senator Adam Schiff of California and New York Attorney General Letitia James, who brought a civil fraud lawsuit against Trump and his company, and ex-Trump prosecutor Jack Smith faces an investigation from an independent watchdog office. Schiff and James have vigorously denied any wrongdoing through their lawyers.

The Bolton searches also unfolded against the backdrop of a 2022 search for classified documents at Trump’s Mar-a-Lago estate in Palm Beach, Florida, an action that produced since-dismissed criminal charges but remains the source of outrage for the president and supporters who insist he was unjustly targeted despite the retrieval of top-secret records.

Patel said in a Fox Business Channel interview this week that the Mar-a-Lago search represented a “total weaponisation and politicisation” of the bureau, and Trump himself referenced it on Friday, telling reporters: “I guess his house was raided today, but my house was raided, also.”

Bolton served as Trump’s third national security adviser for 17 months and clashed with him over Iran, Afghanistan and North Korea. (AP)