Taliban kidnappers have shot dead a second Korean hostage and have threatened to kill more of the 21 they are still holding.

The terrorist group has set another deadline for Kabul to free rebel prisoners, saying more of the Koreans would be shot if their demands were not met.

The blood-stained body of a male Korean hostage - identified as Shim Sung-min, 29, an IT worker who did volunteer work to help the poor - was found dumped on a clover field beside a road in Arzoo, near the town of Ghazni.

The Taliban shot Shim after other deadlines they set for the release of rebel prisoners expired. Taliban spokesman Qari Mohammad Yousuf said Shim was killed because Afghan authorities were ignoring their demands.

He said: "If the Kabul administration and Korean government do not give a positive reply to our demand about the release of Taliban prisoners by tomorrow 1200 (local time), then we will start killing other hostages."

He said Afghan negotiators had not contacted the Taliban since the second hostage was killed on Monday evening and said the insurgents suspected the Afghan government and foreign troops were intending to launch a rescue bid.

Any attempt to rescue the hostages by force would put the Korean's lives at risk, he warned.

Police cordoned off the site in the village of Arzoo where his body was found fearing it could have been booby trapped, but managed to recover it later.

The village is some 50 miles from where the group of 18 women and five men were seized near Qarabagh on the main highway south from Kabul.

Shim's mother cried hysterically after hearing the victim may have been her son. She said: "Why did you kill him? Please save his life."

Shim's father, a provincial assembly member, described his son as a gentle soul. He said: "He had a good heart and did a lot of volunteer work. My son wanted to help the poor and disabled."

A Western security analyst said negotiations to free the hostages are at an impasse. Afghan authorities are demanding the release of the 18 women before any prisoners are freed and the kidnappers insist its fighters should be let out of jail first.

On Wednesday, the Taliban killed the leader of the Korean Christian group.