CNN, Politico and MS NOW have sued the Trump administration after the three US media outlets were barred from the White House.

President Donald Trump announced the ban on Friday, accusing the organisations of writing “fiction or lies” about his team. The companies said their reporters were denied access to the building on Saturday.

In a joint statement on Monday, they said they were pursuing legal action to “defend the principle that the government does not decide what the press reports”.

Major US TV networks later announced they would suspend their White House pooled coverage of Trump, leaving a potential gap as he heads to New York for the United Nations General Assembly.

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 statement from CNN, Politico and MS NOW 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.”

The media organisations filed the lawsuit on Monday in US District Court in Washington, asking a judge to quickly rule Trump’s ban unconstitutional and prevent his aides from enforcing it.

Earlier, in a posting on Truth Social, Trump said the White House was not “instituting an assault on the Free Press” and that he was targeting “FAKE NEWS”.

On Monday morning, major US TV networks pulled out of White House pool duties, which sees media organisations share material with each other to save on costs and space when broadcasting presidential events to the American public.

Fox News Washington bureau chief Bryan Boughton, who currently holds a rotating role helping to organise media TV crews covering the White House, wrote in an email seen by the BBC that “effective today, the TV pool will not be covering designated as pool coverage” of President Trump.

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