The US Department of Justice (DoJ) has said it is investigating several TV networks over whether they broke federal competition laws when they recently suspended pool coverage of Donald Trump.

Last month, five networks paused their presidential coverage for several days in response to the Trump administration withdrawing the credentials of reporters from CNN, MS Now and Politico.

The DoJ asked ABC, CBS, CNN, NBC and Fox News to hand over communications related to the pool and said the boycott could violate the Sherman Act, referring to a law that bars companies from engaging in monopolistic business practices.

Pool members usually share their material with the wider media.

A DoJ spokesperson said: “The Antitrust Division is simply investigating to determine whether these ​news organisations have violated the antitrust laws.”

The television networks have not yet commented.

Trump blocked CNN, MS Now and Politico from the White House last month after accusing the organisations of writing “fiction or lies” about his team.

The White House later reinstated their access following a judge’s ruling. The three outlets had sued the Trump administration, arguing the restricted access violated their First Amendment rights.

The First Amendment forbids the government from “abridging” the freedom of the press – language that courts have traditionally interpreted as preventing the government from discriminating against the media based on the content of their coverage.

The Trump administration has taken a number of legal actions against news publications in the US, including lawsuits over coverage of the president.

In February, the White House announced it was taking control of the press pool, which has access to Trump and had for more than a century been managed by the White House Correspondents’ Association.

The same month, the Trump administration moved to bar Associated Press (AP) reporters and photographers from spaces where access is limited, such as the Oval Office or Air Force One, because of the outlet’s usage of the term “Gulf of Mexico” instead of “Gulf of America”. AP filed a lawsuit and the case remains ongoing.