Nineteen South Koreans held hostage for six weeks in Afghanistan are kept on the move by their Taliban captors, but are said to be in good health, a doctor in touch with a senior commander in the insurgent group told reporters Friday.

Earlier this month, Dr. Mohammad Hashim Wahaaj delivered medicine to the Taliban to give to the South Koreans. He said he was not allowed to examine the hostages, but discussed any medical concerns over the phone with their captors.

Wahaaj told a media conference he remained in regular telephone contact with Mullah Mansor, the Taliban commander in the area where the South Korean aid workers were kidnapped on July 19.

He said Mansor had told him the South Koreans "were fine and have no medical problems," but were split into several groups and moved around every "six to eight hours" to stay one step ahead of Afghan security forces.

The Taliban originally seized 23 South Koreans, but have since killed two of the hostages and released two others. They are demanding the withdrawal of South Korean troops from the country and the release of prisoners in exchange for freeing the hostages.

There are around 200 South Korean troops in Afghanistan, most of them medics and engineers.

Wahaaj, who runs a health clinic in the Afghan capital Kabul, also appealed to the Taliban to allow him to treat or deliver medicine to a German engineer and four Afghans kidnapped more than a month ago.

The German appeared in a video broadcast on Afghan television on Thursday apparently in pain, lying on the ground, coughing and holding his chest.

"We want this person to be treated," Wahaaj said. "If he is healthy, you (the Taliban) can still talk. If he dies, you will lose everything."

Wahaaj said he was working on his own initiative, prompted by humanitarian concerns. The Afghan government has said it has no objections to his efforts.

Insurgents in Afghanistan are increasingly using kidnappings of government officials or foreign aid workers as part of their campaign to overthrow the Western-backed government that took power after the defeat of the Taliban in 2001. Violence in Afghanistan is running at its highest level since the Taliban ouster.

The militant shot Friday was killed while "attempting to engage coalition and Afghan forces" during a raid in Nangarhar province, the coalition statement said. Eleven other men detained during the operation will be questioned "as to their involvement in militant activities," it said.

Troops recovered weapons and ammunition during the raid, the statement said.