TOKYO (AP) _ An actor who was mistakenly slashed in the neck with a real sword during filming of a samurai drama died today of circulatory failure, police and hospital officials said.

Yukio Kato, 34, was unconscious and in serious condition when he was hospitalized Dec. 26 in Okayama, 340 miles west of Tokyo, said a hospital official who spoke on condition of anonymity.

Police said Kato had allegedly been slashed in the neck with a real sword by Takehiro Okumura, another actor, during filming of the traditional Japanese movie.

They said a real sword had been accidentally substituted for a fake one during the filming. According to local news reports, the director of the movie, Shintaro Katsu, father of Okumura, had ordered the crew to replace the fake sword because it was in poor condition.

Police said investigations were under way and they had confiscated the sword and reels of film containing the battle scene.