CNN has threatened the Trump administration’s Department of Justice with further legal action over restrictions related to Air Force One coverage, escalating a long-running dispute between the White House and major American news organisations over press access to the president.

In a letter from the network’s lawyer, CNN argued that Air Force One and the Oval Office are central locations for presidential interactions with journalists. The letter cited figures indicating President Donald Trump had answered more than 4,700 questions at those two locations and on the White House tarmac since the start of his second term, compared with roughly 150 questions answered in the White House press briefing room.

CNN had been scheduled to serve as the primary television representative in the press pool during the president’s activities in Washington on Tuesday, but it was excluded from the pool covering a planned trip to South Carolina. Four other major networks — ABC, CBS, Fox and NBC — reportedly declined to take CNN’s place, leaving conservative broadcaster Real America’s Voice to cover the trips as the secondary television representative.

The Department of Justice had not responded to a request for comment at the time of the reports. The latest move marks another phase in the legal fight over how the administration allocates pooled access to presidential travel.