By Mike Scarcella

(Reuters) -Elon Musk’s social media platform X won on Wednesday an appeal to partially block a California law requiring social media companies to publish their policies for combating disinformation, harassment, hate speech and extremism.

A three-judge panel of the 9th U.S. Circuit Court of Appeals in San Francisco overturned a lower court judge's decision declining to pause enforcement of the new California law.

The law requires large social media companies to issue public reports describing their content moderation practices and to provide data on the number of objectionable posts and how they were addressed.

Musk sued last year to stop the law from taking effect, claiming it violated speech protections under the U.S. Constitution’s First Amendment.

X and its lawyers did not immediately respond to requests for comment on the decision. The California attorney general’s office, which defended the measure, also did not immediately respond to a request for comment.

X's case is among several legal challenges over the extent of states' authority to regulate social media companies.

The U.S. Supreme Court in May directed lower courts to reassess whether social media content moderation laws in Texas and Florida raised First Amendment concerns.

In X's lawsuit, U.S. District Judge William Shubb in Sacramento refused to block the California law in December, finding it was not "unjustified or unduly burdensome within the context of First Amendment law.”

The appeals court disagreed, holding that the law's requirements were "more extensive than necessary" to justify the state's goal of forcing social media companies to be open about their moderation policies and practices.

The panel said the lower court must review whether the content moderation part of the law can be carved out from other provisions.

(Reporting by Mike Scarcella;Editing by David Bario, Leslie Adler and Emelia Sithole-Matarise)