The FBI raided the home of a Washington Post reporter early Wednesday in what the newspaper called a “highly unusual and aggressive” move by law enforcement.

Agents descended on the Virginia home of Hannah Natanson as part of an investigation into a government contractor accused of illegally retaining classified government materials. The Post is “reviewing and monitoring the situation”, a source at the newspaper told the Guardian.

“It’s a clear and appalling sign that this administration will set no limits on its acts of aggression against an independent press,” Marty Baron, the Post’s former executive editor, told the Guardian.

The reporter’s home and devices were searched, and her Garmin watch and phone seized. A warrant obtained by the Post cited an investigation into Aurelio Perez-Lugones, a system administrator in Maryland with a top secret security clearance who has been accused of accessing and taking home classified intelligence reports.

Natanson, the Post said, covers the federal workforce and has been a part of the newspaper’s “most high-profile and sensitive coverage” during the first year of the second Trump administration.

As the paper noted in its report, it is “highly unusual and aggressive for law enforcement to conduct a search on a reporter’s home”.

In a first-person account published last month, Natanson described herself as the Post’s “federal government whisperer”, and said she would receive calls day and night from “federal workers who wanted to tell me how President Donald Trump was rewriting their workplace policies, firing their colleagues or transforming their agency’s missions”.

“It’s been brutal,” the article’s headline said.

Natanson said her work had led to 1,169 new sources, “all current or former federal employees who decided to trust me with their stories”. She said she learned information “people inside government agencies weren’t supposed to tell me”, saying that the intensity of the work nearly “broke” her.

The federal investigation into Perez-Lugones, the Post said, involved documents found in his lunchbox and his basement, according to an FBI affidavit.

The justice department did not immediately return a request for comment.

In a statement, Bruce D Brown, president of the Reporters Committee for Freedom of the Press, condemned the raid.

“Physical searches of reporters’ devices, homes and belongings are some of the most invasive investigative steps law enforcement can take,” he said.

“There are specific federal laws and policies at the Department of Justice that are meant to limit searches to the most extreme cases because they endanger confidential sources far beyond just one investigation and impair public interest reporting in general.

“While we won’t know the government’s arguments about overcoming these very steep hurdles until the affidavit is made public, this is a tremendous escalation in the administration’s intrusions into the independence of the press.”