U.S. Attorney General William Barr has appointed a federal prosecutor to examine the origins of the investigation into Russian interference in the 2016 presidential election, the Associated Press reports.
The news agency quoted an unidentified person familiar with the matter as saying on May 13 that John Durham, the U.S. attorney in Connecticut, has been assigned to determine whether the collection of intelligence on the Trump campaign was "lawful and appropriate."
President Donald Trump has called for such an investigation, branding the Russia inquiry a "witch-hunt" by his opponents.
Trump and his supporters have also accused the Justice Department and the FBI of illegally spying on his campaign.
Meanwhile, critics of Barr have accused the attorney general of acting on behalf of the president rather than in the interests of justice.
Durham, who was nominated for his U.S. attorney's post by Trump, has a background in investigating law enforcement wrongdoing and corruption.
His inquiry is said to be separate from a probe by the Justice Department's inspector general into the genesis of the Russia investigation.
Durham’s appointment comes after Barr told congressmen last month he believed "spying did occur" on the Trump campaign.
"The question is whether it was adequately predicated. And I'm not suggesting that it wasn't adequately predicated. But I need to explore that," he added, without providing details.
The AP news agency said that Barr appeared to be alluding to a surveillance warrant the FBI obtained to monitor former Trump campaign adviser Carter Page and the agency’s use of an informant while it was investigating an ex-foreign policy aide to the Trump campaign, George Papadopoulos.
Barr later said he was gathering a team to look into the origins of the Russia investigation, which was led by Special Counsel Robert Mueller.
Mueller's final report has concluded that Russia interfered in the 2016 election "in sweeping and systematic fashion," using an extensive social media campaign and hacking into Democratic Party servers.
However, there was not sufficient evidence to prove Trump and his team committed a crime by colluding with Russian officials to tip the outcome of the vote, according to the report.
The Kremlin has denied interfering in the election.
Meanwhile, leading Democrats have demanded that the Mueller report be published in full, and a House committee earlier this month voted to hold Barr in contempt for not handing over the full, unredacted Mueller report.
Several Democratic-led committees in the House have ongoing investigations related to the findings released in Mueller's report.