In a video aired on Friday night, the self-styled Islamic Army said it also captured a bodyguard of Chalabi during Wednesday's attack.
The purported hostage says in the video that three of his colleagues were killed in the assassination attempt. The captive talks about "Chalabi's relations with the American Congress and Iran".
The group, which is also believed to have kidnapped two French journalists, said in the video that "the hostage, who was wounded during the attempted assassination of Chalabi, died as a result of his wounds".
Chalabi, head of the Iraqi National Congress and a member of the now dissolved Iraqi Governing Council, escaped unharmed in the attack in which two of his bodyguards were killed, two wounded and another two went missing.
"I was coming back from Najaf, where I met Grand Ayat Allah Ali al-Sistani the previous day, and when we reached Latifiya, a car started following us and opened fire on our convoy," Chalabi said after the attack.
Among other developments, hopes have been rising for the release of two French journalists, Christian Chesnot and Georges Malbrunot, being held captive by an Iraqi group.
Jean de Belot, the chief editor of French daily Le Figaro, has told Aljazeera that he has received word that the journalists are alive and well.
Quoting French Interior Minister Dominique de Villepin, Belot said the Islamic Army had handed the reporters over to an Iraqi resistance group thought to be more inclined to set them free.
The group is said to be willing to
negotiate the reporters' release
The group is believed to be willing to negotiate their release.
A spokesman for the highest Sunni authority in Iraq, the Association of Muslim Scholars, also said on Friday that were safe and would be released soon.
"Their release could just be a matter of time," said Shaikh Abd al-Salam al-Kubaisi.