Families of the South Korean hostages wailed in anguish Tuesday at learning that a second of the captives had been executed by Taleban insurgents.

South Korea's Foreign Ministry confirms that the insurgents shot and 29-year-old Shim Sung-min.

Foreign Ministry Spokesman Cho Hee-yung says South Korea cannot hide its anger against the Taleban for this "merciless killing."

Shim was among 23 South Korean Christian activists abducted by Taleban militants Afghanistan more than a week ago. His death follows the militants' execution Thursday of the group's 42-year-old pastor.

Even as the South Korean authorities were confirming Shim's death, the insurgents announced a new deadline mid-day Wednesday Afghan time for meeting their demands.

The captors want the Afghan government to free a number of fellow insurgents being held in Afghan prisons in exchange for the hostages.

South Korea has a senior envoy to Kabul to work with Afghan President Hamid Karzai on the crisis. But South Korean presidential spokesman Chun Ho-seon says Seoul can only do so much.

Chun says South Korea has influence on the Afghan government, which so far refuses to free any Taleban prisoners. He calls on the Taleban to stop asking South Korea for things it is unable to deliver.

Chun says South President Roh Moo-hyun is still firmly opposed to military action to free the hostages - but he adds that South Korea's patience is not endless.

Chun says if the Taleban kill more Korean civilians, Korea will not just sit idle and watch. He does not say what other action the Roh administration might take.

Families of the hostages read their own statement on live television Tuesday, calling for .S. help in the situation.

Kim Kyung-ja, mother of one of the surviving hostages, asks the United States to consider the hostage issue from a humanitarian, rather than a political, perspective.

The U.S. leads multinational and stabilization efforts in Afghanistan, which South Korea supports with several hundred non-combat personnel. Some South Koreans have criticized Washington for refusing to use its influence to persuade Kabul to meet the captors' demands.

generally refuses to negotiate, however, with those it considers terrorists - including the Taleban, which sheltered leaders of the al-Qaida terrorist network as they planned the September 11, 2001 attacks on New York and .

Five Taleban prisoners were freed by the Afghan government in March in a deal that saved the life of an Italian journalist kidnapped by the Taleban. The release was widely condemned, by U.S. officials others, and President Karzai said it would not be repeated.