The Trump administration reportedly secretly obtained the phone records of newspaper journalists who reported on allegations of Russian meddling in the 2016 election.
The Washington Post said the US Justice Department sent letters to three of its reporters - Ellen Nakashima and Greg Miller, and former Post reporter Adam Entous - saying that it had received work, mobile or home phone records "for the period from April 15, 2017 to July 31, 2017."
The newspaper's acting chief executive, Cameron Barr, said the 'paper was "deeply troubled by this use of government power to seek access to the communications of journalists."
He said: "The Department of Justice should immediately make clear its reasons for this intrusion into the activities of reporters doing their jobs, an activity protected under the First Amendment."
The American Civil Liberties Union said the Justice Department had been "spying" on the journalists "at the whims of an administration."
It tweeted: "This should never have happened. When the government spies on journalists and their sources, it jeopardises freedom of the press."
The Justice Department shouldn't go spying on journalists at the whims of an administration.— ACLU (@ACLU) May 8, 2021
This should never have happened.
When the government spies on journalists and their sources, it jeopardizes freedom of the press. https://t.co/V6BLYidxF2
The Washington Post quoted a Justice Department spokesperson as saying that the Department had followed "established procedures" with the requests.
The letters did not specify why the records were seized.
But, near the end of that period, the three wrote a story about US intelligence which suggested that Jeff Sessions, who later became attorney general under Donald Trump, had discussed the Trump campaign with the Russian ambassador.
They also wrote a story on the Obama administration's efforts to counter Russian interference in the 2016 election.
US intelligence agencies have concluded Russia hacked into the computer servers of the Democratic National Committee (DNC) during Mr Trump's campaign against Democratic rival, Hillary Clinton.
Former president Trump has played down Russia's involvement in the DNC leak, famously appearing to side with President Vladimir Putin of Russia over his own intelligence agency's assessment.