Updated

A purported Taliban spokesman claimed the hardline militia killed a second Korean hostage Monday because Afghanistan failed to release insurgents from prisons. Government officials said they hadn't recovered the body and couldn't confirm the claim.

Meanwhile, the Al-Jazeera TV channel showed a video Monday of some seven South Korean female hostages. They did not speak as the shaky hand-held camera filmed them crouching with veiled heads in the dark, eyes closed or staring at the ground.

The pan-Arab satellite station did not say how it obtained the video, and its authenticity could not immediately be verified.

Militant spokesman Qari Yousef Ahmadi said senior Taliban leaders decided to kill the male captive because the government had not come through on promises to release Taliban prisoners.

"The Kabul and Korean government are lying and cheating. They did not meet their promise of releasing Taliban prisoners," Ahmadi, who claims to speak for the Taliban, said by phone from an undisclosed location. "The Taliban warns the government if the Afghan government won't release Taliban prisoners then at any time the Taliban could kill another Korean hostage."

Ghazni Gov. Marajudin Pathan said officials were aware of the Taliban's claim but hadn't recovered a body. He said police were looking but he couldn't say if they might find anything before daybreak.

"Ghazni is a very vast area, so we really don't know where the body is," Pathan said.

The Taliban kidnapped 23 South Koreans riding on a bus through Ghazni province on the Kabul-Kandahar highway on July 19. The militants have told the government they want 23 Taliban prisoners released from jail in exchange for the Koreans' lives.

The Taliban has set several deadlines for the Koreans' lives. Last Wednesday the insurgents killed their first hostage, a male leader of the group.

The body of Pastor Bae Hyung-kyu arrived back in South Korea on Monday, where the families of the remaining hostages pleaded for their loved ones' release.

Relatives gathered at Saemmul Community Church in Bundang, just outside Seoul, and waited anxiously for developments — sharing prayers, meals and sleepless nights as they followed 24-hour television newscasts.

Seo Jung-bae, 59, whose daughter and son were among the detainees, appealed to the Taliban for their release.

"Please, please send my children back so I can hold them in my arms," he told The Associated Press, fighting back tears in a plea to the captors. "Our families are the same. Your family is precious, so is mine."

Speaking from an emergency center set up by the church, he said his children had traveled to the country's dangerous south to assist Afghans in need. "They went there to help, thinking they (Afghans) are their friends."

It's not clear if the Afghan government would consider releasing any militant prisoners. In March, President Hamid Karzai approved a deal that saw five captive Taliban fighters freed for the release of Italian reporter Daniele Mastrogiacomo. Karzai, who was criticized by the United States and European capitals over the exchange, called the trade a one-time deal.

Earlier on Monday Ahmadi said the Taliban had extended two deadlines for the Koreans lives. His claim that the militants killed a second hostage came several hours after the second deadline passed.

Pathan said that authorities talked to the Taliban on Sunday after they set the latest deadline and asked for two more days of talks.

The attempts to free the South Koreans come after Karzai and other Afghan officials tried to shame the Taliban on Sunday into releasing the 16 female captives by appealing to a tradition of cultural hospitality and chivalry.

Elsewhere, Taliban militants ambushed a convoy of private security guards on a dangerous highway south of the capital, and officials said Monday up to 13 guards were killed.

NATO's International Security Assistance Force said the ambush was against civilians, but Afghan officials said the attack came against private security guards on the Kabul-Kandahar highway Sunday, the same roadway where the South Koreans were kidnapped.

The Taliban attack Sunday sparked a three-hour gunbattle and resulted in the deaths of 13 private security guards and five Taliban militants, said Jailani Khan, the commander of highway police in Zabul province.

Gulabshah Alikhail, the governor's spokesman, said seven guards were killed and five wounded, while an Interior Ministry statement said 10 private guards were killed.

NATO's ISAF reported that Romanian soldiers came upon a civilian convoy ambushed by the Taliban and that 12 civilians were killed and eight wounded.