SAN FRANCISCO — Twitter Inc. has sued to block an attempt by federal officials to unmask the person or people behind @ALT_USCIS, one of the so-called “alternative agency” Twitter accounts critical of Trump administration policies that have popped up over the past few months.

Like many of the alternative agency accounts, @ALT_USCIS claims that it is run by an individual currently employed by the federal government, in this instance the U.S. Citizenship and Immigration Services. According to the complaint filed Thursday by a team at Wilmer Cutler Pickering Hale and Dorr, the account attracted more than 32,000 followers in less than two months of existence with its mix of political commentary and often critical observations about the agency.

“Compelling Twitter to disclose information that would identify or lead to the identification of the person(s) who established and use the @ALT_USCIS account would chill the expression of particularly valuable political speech—namely speech by current or former public employees, or others with special insight into operations of our government,” wrote the Wilmer lawyers.