An American journalist kidnapped by militants in Iraq and threatened with death said in a video aired Friday that his captors were treating him well.

The video was broadcast on the Arab television station Al-Jazeera as a top aide to firebrand Shiite cleric Muqtada al-Sadr (search) said the kidnappers had told him Friday they would free Micah Garen (search) later in the day.

"I am an American journalist in Iraq and I've been asked to deliver a message," the man, identified as Garen, a New York-based journalist, said on the video. "I am in captivity and being treated well."

The newsreader said that Garen also had called for an end to the killing in Najaf, where U.S. and Iraqi forces have been fighting a radical Shiite militia for two weeks, though that part of the audio was inaudible.

According to witnesses, Garen and his Iraqi translator, Amir Doushi, were walking through a market in the southern city of Nasiriyah on Aug. 13 when two armed men in civilian clothes seized them, police said. There was no word on Doushi's fate.

Al-Jazeera reported Thursday that a militant group calling itself the Martyrs Brigade (search) had abducted Garen and would kill him within 48 hours unless U.S. troops pull out of the holy city of Najaf.

Sheik Aws al-Khafaji, a top al-Sadr aide said he had spoken to the kidnappers, who told him they would release Garen later Friday. "The kidnappers have put the journalist in a safe place," al-Khafaji said from Nasiriyah.

The family of Turkish hostage Aytullah Gezmen, meanwhile, was anxiously praying for his release Friday, a day after two Turkish companies withdrew from Iraq in a bid to save his life.

A Turkish television channel on Thursday broadcast a video of Gezmen and said the kidnappers threatened to kill him if the companies didn't leave Iraq within three days.

"We're so worried. We don't understand why they did not release him yet," Sevim Gezmen, a sister-in-law, said by telephone Friday from the family's home in southern Turkish city of Iskenderun. "Time is running out and we have no means to make sure that they have heard that the companies have withdrawn from Iraq."

Garen was working on a story about the looting of archaeological sites in Iraq when he was abducted, said his fiancee, Marie-Helene Carleton.

In calling for Garen's release, al-Khafaji said Thursday that the militia was against kidnapping, "especially this journalist who rendered Nasiriyah great service."

Another official in al-Sadr's office, speaking on condition of anonymity, also said al-Sadr officials had contacted the kidnappers. But he said Garen would only be released "after the crisis in Najaf is defused."

British journalist James Brandon was kidnapped and similarly threatened with death last week, but freed the next day after a public appeal by al-Sadr's aides, including al-Khafaji.

Thousands of U.S. troops are deployed in Najaf, whose revered Imam Ali Shrine is the holiest in Iraq for Shiite Muslims. U.S. officials have repeatedly said that they would not give into the demands of kidnappers, and any U.S. withdrawal from the city was highly unlikely.

State Department spokesman Adam Ereli said Thursday that the United States was doing everything possible to find Garen.

"Our objective is to bring about the safe release of this innocent victim of terror, and we'll continue to do everything we can to bring that about," Ereli said.

Garen's sister Eva appealed to the kidnappers in a phone interview with Al-Jazeera on Thursday, saying that she hoped they would free her brother after hearing the request for his release from al-Sadr's aides.

Garen worked for Four Corners media, identified on its Web site as a "documentary organization working in still photography, video and print media."

He has taken photographs as a stringer for The Associated Press and had a story published in The New York Times. His photographs also have appeared in U.S. News & World Report.