WASHINGTON (AP) _ If death row inmate Lloyd Schlup gets another chance to prove he's innocent, a wave of new appeals would swamp the nation's courts, the Missouri Attorney General told the Supreme Court today.

''It would open up the floodgates,'' Missouri Attorney General Jay Nixon told the justices.

Schlup's lawyers contend the high standards required by federal courts for new evidence to be introduced in death penalty appeals is too tough and could result in executions of innocent people.

''His case exemplifies the injustice that can occur when poor people accused of crime are denied adequate legal representation,'' said Schlup's attorney, Sean O'Brien.

The justices appeared divided in their questions today, with some exploring the facts of Schlup's case and others asking whether it was proper for federal courts to second-guess jury verdicts.

''You used to have a thing called finality,'' said Justice Antonin Scalia. ''Of course you (defendants) come in and say you're innocent, but you've had a trial.''

Schlup, 33, was sentenced to die for the February 1984 stabbing death of fellow prison inmate Arthur Dade. Nixon said Schlup is a white supremacist and former member of the Aryan Nation; Dade was black.

Schlup consistently has proclaimed his innocence, relying on a prison videotape showing he was eating lunch when guards in the dining room were summoned to the Dade attack.

Prosecutors discounted the videotape, persuading a jury that Schlup had ample time to attack Dade and make it back to the nearby dining room. His first round of appeals were rejected and he came within eight hours of execution last November before a reprieve by Missouri Gov. Mel Carnahan.

The stay came after Schlup's attorneys produced two affidavits not introduced during his trial from a former guard and an inmate, again indicating he wasn't guilty.

The former guard, Robert Faherty, said he saw Schlup walking slowly down a corridor around the time of Dade's slaying and that he appeared calm. Inmate John Green said he witnessed the attack and insisted Schlup wasn't involved.

O'Brien said Schlup wanted his previous court-appointed lawyers to interview the pair, but no one did until his case was on appeal in 1992.

Carnahan appointed a panel of three retired judges to review the new evidence. But before they finished, the Supreme Court agreed to decide the matter.

Since 1970, 48 people have been released from death sentences nationwide because of strong evidence of innocence, according to the Death Penalty Information Center. Most often, the reversal came after a new lawyer discovered critical mistakes during the trial.

Current practices could condemn other innocent inmates to death, said Richard Dieter, executive director of the center.

''Once a conviction has been obtained, however unfairly, the odds are stacked against the defendant who may be innocent,'' Dieter said. ''Mistakes are inevitable and almost impossible to rectify.''

But Nixon said the higher standard keeps out dubious proof and prevents endless delays.

''We must support a review standard designed to require a high level of proof that will minimize suspect evidence and protect the sanctity of the jury process,'' he said.