Twitter Inc. and Facebook will be compelled to allow the dissemination of Russian propaganda as well as neo-Nazi and Ku Klux Klan screeds denying the Holocaust unless a Texas social media law is blocked, tech groups representing the companies told the U.S. Supreme Court.

The emergency filing Friday seeking to block the Texas law — HB20 — comes two days after a divided federal appeals court let it take effect while a legal challenge filed by the tech groups goes forward. The New Orleans-based 5th U.S. Circuit Court of Appeals’ order, which came without explanation, put on hold a temporary injunction a trial judge issued in December.

"The 5th Circuit short-circuited the normal review process, authorizing Texas to inflict a massive change to leading global websites,” the tech groups said in the filing. "The cost of revamping the websites’ operations would undo years of work and billions of dollars spent on developing some platforms’ current systems.”