BONNE TERRE, Mo. — Justice Samuel A. Alito Jr. of the United States Supreme Court late Tuesday issued an order halting the planned execution of a Missouri inmate.

Justice Alito’s order did not offer an explanation of why he had suspended the scheduled execution of Russell Bucklew, but it indicated that he or the Supreme Court would have more to say about the matter.

The order was issued shortly after the full United States Court of Appeals for the Eighth Circuit lifted a stay of execution granted hours earlier by a three-judge panel of that court. The panel had issued the stay over concerns that a rare medical condition Mr. Bucklew has could cause him undue suffering during the lethal injection.

Mr. Bucklew was scheduled to die by lethal injection at 12:01 a.m. Wednesday.

The 2-to-1 ruling by the panel said Mr. Bucklew’s “unrebutted medical evidence demonstrates the requisite sufficient likelihood of unnecessary pain and suffering beyond the constitutionally permissible amount inherent in all executions.”