The Trump administration secretly obtained the phone records of Washington Post journalists who reported on allegations of Russian meddling in the 2016 election, the newspaper reported Friday, prompting concerns over freedom of speech. 

The Justice Department sent letters to three reporters -- Ellen Nakashima and Greg Miller, and former Post reporter Adam Entous -- saying that it had received work, cell or home phone records "for the period from April 15, 2017 to July 31, 2017," according to the Post.

The newspaper was "deeply troubled by this use of government power to seek access to the communications of journalist," Post acting executive editor Cameron Barr was quoted as saying.

"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," he continued.

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 Trump's campaign against Democratic rival Hillary Clinton.