KANDAHAR, Afghanistan — The Taliban threatened to begin killing 23 South Korean hostages today if the government doesn't free insurgents held in prison. The demands came as the U.S.-led coalition reported killing some 50 militants in southern Afghanistan's poppy-growing heartland.

Khail Mohammad Husseini, a lawmaker from Ghazni province, where the Koreans are being held, said provincial leaders tried to meet with the kidnappers today but that they didn't show. He said the Taliban increased their demands by telephone, saying all militant prisoners in Ghazni now had to be released.

Qari Yousef Ahmadi, who claims to speak for the militia, disputed that report, saying the Taliban were still demanding the release of 23 prisoners.

"If the government won't accept these conditions, then it's difficult for the Taliban to provide security for these hostages, to provide health facilities and food," Ahmadi told The Associated Press by satellite phone. "The Taliban won't have any option but to kill the hostages."

Ahmadi said Sunday that the militants were giving the Afghan and South Korean governments until 10:30 a.m. EDT today to respond to their demands.

Deputy Interior Minister Abdul Khaliq said Afghanistan was not prepared to make a deal "against our national interest and our constitution," although he did not explicitly rule out freeing any prisoners.

President Hamid Karzai in March authorized the release of five Taliban prisoners in exchange for a kidnapped Italian reporter, but called the trade a one-time deal. Karzai was heavily criticized for the move by the United States and European nations, who felt it would encourage more kidnappings.

South Korea has about 200 troops serving with the 8,000-member coalition in Afghanistan, largely working on humanitarian projects. They are scheduled to leave Afghanistan at the end of 2007.