Palestine TV on Saturday broadcast footage of the interrogation of a prisoner who Hamas claimed had been tortured to death by rival security forces loyal to Chairman Mahmoud Abbas.
The prisoner seemed to have suffered no visible injuries.
The broadcast was the latest in increasingly ferocious attempts by Hamas and Abbas' Fatah movement to undermine each other's credibility. Hamas seized Gaza by force in June, defeating Abbas' forces.
In the videotape, the prisoner, Moayad Bani Odeh, was only shown from the waist up. He said he had not been mistreated, though it was unclear whether he was speaking under threat.
The date marking on the video was Friday, the same day Ismail Haniyeh, the prime minister from Hamas deposed by Abbas, claimed in a speech Bani Odeh was tortured to death in a West Bank prison.
Bani Odeh, 25, told interrogators that he had joined Hamas in 2002, and began collaborating with the Israeli security forces. In 2003, Bani Odeh said, he gave Israel information that led to the killing of five fugitives, including three from Hamas, in his home village of Tamoun in the West Bank.
In his speech Friday, Haniyeh had referred to Bani Odeh as a "holy warrior."
In broadcasting the Bani Odeh statement, Palestine TV also ran Haniyeh's comments about the prisoner.
In a further twist, Palestinian legislator Khaleda Jarrar said she had been misled about Bani Odeh by Tawfiq Tirawi, head of the general intelligence service.
Jarrar said she had called Tirawi on Thursday, at the request of Bani Odeh's family, to check a rumor that the prisoner was in serious condition.
She said Tirawi told her Bani Odeh was indeed in serious condition in Israeli hospital. In a second phone call shortly afterwards, Tirawi told her Bani Odeh is clinically dead, Jarrar said.
The lawmaker, who is from a small PLO faction, said Tirawi called her on Friday to tell her Bani Odeh was fine, and that he apologized to her.
"We asked to see the young man, and we will ask to see him," Jarrar said Saturday. "We don't care about what's on TV."
Tirawi could not immediately be reached for comment.
Hamas spokesman Sami Abu Zuhri said Saturday that "this is a fabricated story, aimed at harming the image and credibility of the movement." He did not elaborate.