The US Supreme Court on Friday denied a request by the Biden administration to lift a block in several Republican states on expanding sex discrimination protection to transgender students.

President Joe Biden's administration moved in April to extend rules forbidding sex-based discrimination in schools to cover gender identity.

Courts in 10 Republican-controlled states temporarily blocked the rules, and the administration petitioned the Supreme Court to intervene.

But in a 5-4 decision, the judges declined to take action while the legal process at the state level is still playing out.

Conservative justice Neil Gorsuch and the court's three liberal justices issued a partial dissent.

The protections were part of a larger set of new rules on anti-discrimination, all of which will remain blocked in the Republican states while the legal challenges proceed.

The dissenting justices wanted the less controversial rules to take effect.

In her dissent, Justice Sonia Sotomayor highlighted that the court's decision "leaves in place preliminary injunctions that bar the Government from enforcing the entire rule -- including provisions that bear no apparent relationship to respondents' alleged injuries."

"Those injunctions are overboard," she added.