US Supreme Court Chief Justice John Roberts said Tuesday that a draft opinion on abortion leaked to the press in an "egregious breach" of trust was authentic, but not the final decision on the matter.

Roberts also said in a statement that he had directed the marshal of the court to launch an investigation into the source of the leak, seen as an extraordinary violation of institutional protocol.

News outlet Politico late Monday published a draft opinion that suggested the conservative-dominated high court was poised to shred nearly 50 years of constitutional protections by striking down the nationwide right to abortion in the United States.

While the consequences of such a ruling reverberated, the method of how the draft, written by Justice Samuel Alito, came into public view has drawn fierce criticism.

Several Republican lawmakers accused liberals of orchestrating the leak in order to incite unrest and sway the opinion of justices, and demanded a comprehensive investigation by President Joe Biden's administration.

"To the extent this betrayal of the confidences of the Court was intended to undermine the integrity of our operations, it will not succeed," Roberts said.

"Court employees have an exemplary and important tradition of respecting the confidentiality of the judicial process and upholding the trust of the Court," the chief justice added.

"This was a singular and egregious breach of that trust that is an affront to the Court and the community of public servants who work here."