The US Justice Department has filed documents that accuse three media outlets banned from the White House of "trafficking in verifiable falsehoods" and reporting which "threatened national security" as it prepared to defend the move in court.

Last week, President Donald Trump barred CNN, Politico and MS NOW from the White House, accusing them of spreading "fake news".

After their reporters had their passes confiscated and were denied access to the building, the three outlets jointly launched legal action, calling the move unconstitutional.

On Wednesday, a judge is set to decide whether to issue an order temporarily lifting the ban, pending a full hearing.

According to a court filing by the Justice Department in a District of Columbia court, the three outlets were issued with a list of "reporting incidents" by the White House ahead of the ban.

The filing cites a number of stories about construction at the White House - including about a security bunker and the building of a new ballroom, as well as a report on an internal information leak investigation.

It goes on to say that "access to the White House is a privilege, not a right".

The three media organisations have argued that the ban breaches their rights under the First Amendment, which forbids the government from "abridging" the freedom of the press.

In a joint statement confirming legal action against the government, they said: "Without notice or process, the White House revoked our journalists' credentials because it objected to our reporting.

"Left unchallenged, this threatens press freedom and the public's right to independent journalism free from government interference."

Major TV networks have withdrawn from a media-sharing arrangement of video and images of the president, known as the pool, in protest over the ban.

Shortly after, the White House launched its own streaming channel, Trump TV, which operates a 24/7 feed of clips of the president.