The US Justice Department says it is investigating whether television networks violated federal antitrust laws over their decision to boycott covering the White House following its decision to pull the credentials of reporters from three news organisations, including CNN.
The networks under investigation, according to the New York Times, are ABC, CBS, CNN, NBC and Fox News.
"Group boycotts among commercial competitors can violate the Sherman Act," a Justice Department spokesperson said on Saturday.
"The Antitrust Division is simply investigating to determine whether these news organisations have violated the antitrust laws."
The networks did not immediately respond to requests by Reuters for comment.
The television networks briefly stopped providing pool coverage of Trump after he banned CNN, Politico and MS Now from the White House.
They later reinstated coverage.
CNN is one of the five news organisations - along with ABC, CBS, Fox News and NBC - that make up the primary White House television pool.
They share the costs of covering the president, take turns organising coverage and share the footage with outlets around the country.
