South Korean officials on Tuesday identified the body of a second male hostage killed by militants in Afghanistan as the captors set a new deadline for the remaining 21 aid workers being held.

Police found the body of  Shim Sung-min, 29, at daybreak Tuesday. The former information technology worker was volunteering with a South Korean church group on an aid mission to the war-torn country.

This undated photo shows Shim Sung-min, the second South Korean hostage killed by the Taliban, who still hold 21.
(Saemmul Church via Yonhap/Associated Press)

"The government expresses deep condolences to his family," Foreign Ministry spokesman Cho Hee-yong said. "We cannot contain our anger at this merciless killing and strongly condemn this."

Purported Taliban spokesman Qari Yousef Ahmadi said the man was killed because the Afghan government failed to release imprisoned insurgents in exchange for the 16 women and six men who were abducted July 19 in Ghazni province.

"The Kabul and Korean governments are lying and cheating. They did not meet their promise of releasing Taliban prisoners," Ahmadi, who claims to speak for the Taliban, told the Associated Press by phone from an undisclosed location.

Ahmadi said the group threatened to kill more hostages if their demands were not met by the latest of several deadlines — noon (3:30 a.m. ET) on Wednesday.

The body was found on the side of the road in the village of Arizo Kalley in Andar District, about nine kilometres west of Ghazni city, said Abdul Rahim Deciwal, the chief administrator in the area.

Leader's body returned to Korea

The latest death comes as the body of group's leader, Bae Hyung-kyu, was returned to his home country. The 42-year-old pastor was shot and killed more than a week ago. 

As news of the latest killing broke, Al-Jazeera broadcast a new video of the hostages. The silent, shaky video footage showed seven women cowering together, but it didn't indicate when or where the footage was taken.

In South Korea, relatives of the hostages gathered in a church in Bundang, near Seoul, to watch 24-hour news broadcasts and console each other. Seo Jung-bae, whose son and daughter are among the captives, said his children went to Afghanistan to help Afghans in need.

"Please, please send my children back so I can hold them in my arms," Seo Jung-bae told reporters, in the hopes that the kidnappers would be made aware of his pleas.

"Our families are the same. Your family is precious, so is mine."

Afghan President Hamid Karzai approved a deal in March that saw five captive Taliban fighters freed for the release of an Italian reporter. Karzai, who faced heavy criticism from Western powers over the exchange, has said the trade was a one-time deal.

With files from the Associated Press