US President Donald Trump is not allowed to block critics on Twitter because he dislikes their views, a federal court has ruled.
A panel of three judges in Manhattan said the president was forbidden from limiting access to his feed under the first amendment of the US Constitution.
The legal challenge was brought by the Knight First Amendment Institute at Columbia University and seven people blocked by Mr Trump after criticising his policies.
In the court's ruling, circuit judge Barrington Parker wrote: "The first amendment does not permit a public official who utilises a social media account for all manner of official purposes to exclude persons from an otherwise-open online dialogue because they expressed views with which the official disagrees."
Mr Trump has more than 60 million Twitter followers and regularly uses his account to attack his critics.
In a series of tweets published earlier on Tuesday, the president branded the UK ambassador to the US "wacky", "very stupid" and "pompous" in the wake of Sir Kim Darroch's leaked critical memos about Mr Trump.
In their ruling, the judges said they were reminding the public "if the first amendment means anything, it means that the best response to disfavoured speech on matters of public concern is more speech, not less".
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Judge Parker said: "The irony in all of this is that we write at a time in the history of this nation when the conduct of our government and its officials is subject to wide-open, robust debate."
Following the ruling, Jameel Jaffer, the institute's director, said public officials' social media accounts are now among the most significant forums for discussion of government policy.
The judges' decision "will ensure that people aren't excluded from these forums simply because of their viewpoints," he said.