The Afghan government has until noon Friday to release captured Taliban fighters in exchange for South Korean hostages or else more Koreans will be executed, a spokesman for the insurgents said. The latest of several Taliban deadlines for the lives of the South Koreans was given Thursday, a day after one hostage, a 42-year-old pastor, was shot dead. The South Korean government expressed outrage at the slaying, and vowed those responsible would be held accountable. One of the 22 surviving hostages, who identified herself as Yo Syun Ju, told an Afghan journalist by telephone all the hostages were sick, the British Broadcasting Corp. reported. She pleaded for help to secure their release. "Tell them to do something to get us released," she said in an interview which was carried out by phone in the presence of the Taliban militants holding her captive and obtained by the BBC.