A federal appeals court has expanded the scope of a ruling that limits the Biden administration's communications with social media companies, saying it now also applies to a top US cybersecurity agency.

The ruling last month from the conservative 5th Circuit US Court of Appeals severely limits the ability of the White House, the surgeon general, the Centers for Disease Control and Prevention and the FBI to communicate with social media companies about content related to Covid-19 and elections that the government views as misinformation.

The preliminary injunction had been on pause and a recent procedural snafu over a request from the plaintiffs in the case to broaden its scope led the court on Tuesday to withdraw its earlier opinion and issue a new one that now includes the US Cybersecurity and Infrastructure Security Agency. That agency is charged with protecting non-military networks from hacking and other homeland security threats.

Similar to the ruling last month, in which the appeals court said the federal government had "likely violated the First Amendment" when it leaned on platforms to moderate some content, the new ruling says CISA violates the Constitution.

"CISA used its frequent interactions with social media platforms to push them to adopt more restrictive policies on censoring election-related speech," the three-judge panel wrote.

"The platforms' censorship decisions were made under policies that CISA has pressured them into adopting and based on CISA's determination of the veracity of the flagged information," they continued. "Thus, CISA likely significantly encouraged the platforms' content-moderation decisions and thereby violated the First Amendment."

The plaintiffs in the suit, which include Missouri and Louisiana's attorneys general, as well as several individual plaintiffs, had also asked the court to expand the scope in other ways, including by making it apply to some State Department officials. But the court's new ruling was only modified to add CISA as an enjoined entity.

The judges said they were pausing their new injunction for 10 days, and the Biden administration has the option of asking the Supreme Court to issue a more lasting pause on the modified ruling.