Twitter has filed suit against the US government, asking a court to back its refusal to hand over the identities of users claiming to be dissenting federal employees.

The lawsuit, filed yesterday, revealed that the Department of Homeland Security and US Customs and Border Protection had sought the unmasking of the @ALT_USCIS account holder who has been criticizing President Donald Trump's administration.

The suit could portend a contentious battle between the social network and the US administration over efforts to crack down on government leaks.

The account in question is purportedly run by one or more current employees of the US Citizenship and Immigration Services (USCIS), a unit within Homeland Security.

It is one of several “alternative” handles apparently created by government workers after Trump's inauguration in January that have sometimes revealed data the new administration sought to suppress or remove from official websites.

“The rights of free speech afforded Twitter's users and Twitter itself under the First Amendment of the US Constitution include a right to disseminate such anonymous or pseudonymous political speech,” the lawsuit says.

It was filed in a California federal court.

The government “may not compel Twitter to disclose information regarding the real identities of these users without first demonstrating that some criminal or civil offense has been committed,” it said.

The so-called social media resistance movement began after the deletion of tweets and data from official US accounts and websites that proved embarrassing to the new president, including government reports about climate change.

After some took to Twitter with “alternative” handles — claiming to be federal employees exercising their free-speech rights — the resistance mushroomed into a movement.

Twitter said it received a summons on March 14 to produce the name or names of the account holder, saying the document asked the company “not to disclose the existence of this summons for an indefinite period of time.”

The company said it contacted the agent who delivered the summons, who “stated vaguely that he is conducting an investigation” but “did not identify any law or laws that he believed had been broken.” (