German hostage appeals
In related news, the Taliban are still holding a German captive they kidnapped a day before the South Koreans.
A man who has identified himself as the German national held hostage in Afghanistan for more than three weeks said on Monday that his Taliban captors wanted to kill him.
The man, who gave his name as Rudolph Blechschmidt, said that he was ill and appealed to the German government to help secure his freedom.
"The Taliban want to kill me," he said.
"I live with Taliban in the mountains," he told the news agency AFP via telephone in an interview arranged by his captors.
"I am in danger also, and I am very sick."
It has not however been possible to independently confirm the man's identity.
The man said his captors wanted to speak directly with the Afghan government and the Germany embassy, and appealed for help to arrange contact with them.
Blechschmidt, a 62-year-old engineer, as identified in the media, was captured on July 18 with a German colleague in the province of Wardak, near to Kabul.
His colleague, a fellow engineer, suffered circulatory failure a few days later and was then shot dead by the Taliban.
Frank-Walter Steinmeier, Germany's foreign minister, made a statement to the media on July 21 in Berlin, saying the ministry had not received independent confirmation.
Four Afghans captured with the engineers are also believed to be held by the Taliban, who have demanded a release of prisoners in exchange for his life.