The US Supreme Court delivered a blow to President Joe Biden on Thursday, blocking his Covid vaccine-or-test mandate for large businesses.

In a divided ruling, the nation's highest court allowed a vaccine mandate for health care workers at facilities receiving federal funding to go ahead.

But the court's six conservative justices ruled against Biden's bid announced in September to make Covid vaccinations or weekly testing compulsory at companies that employ 100 workers or more.

The three liberal justices dissented.

The vaccination mandate for health care workers was approved in a 5-4 vote, with Chief Justice John Roberts and Justice Brett Kavanaugh, both conservatives, joining the three liberals.