An Afghan militant group holding three UN workers said it was losing patience with government and UN negotiators and warned the trio were becoming increasingly cold and sick.
The hostages - Mrs Annetta Flanigan from Co Armagh, Filipino Mr Angelito Nayan, and Ms Shqipe Habibi from Kosovo - were kidnapped on a Kabul street last week.
The Jaish-e Muslimeen (Army of Muslims) has threatened to kill them unless authorities meet a series of demands including the release of all Taliban prisoners, the withdrawal of US troops and the suspension of UN operations in the country.
"It appears the United Nations and the government do not hold the captives' lives dear and their attitude is such that it can cause loss to the captives," Sayed Khalid Agha, a spokesman for the Taliban splinter group, said.
Deadlines came and went yesterday as the kidnappers sought negotiations with authorities, and a clearly angry Agha accused authorities of trying to buy time.
He said the hostages were suffering from cold and lack of food, and all three were ailing. "First one woman fell sick and now all three are sick," he said. "The place where we have kept them is very cold and we also don't have proper arrangements for food. Even if we don't do anything to them, cold alone can severely harm them."
The investigation is officially in the hands of the Interior Ministry and its fledgling police force, with help from the United Nations, Nato-led peacekeepers and US-led forces. Security sources say Britain has sent a hostage specialist team from Scotland Yard.
It is unclear what talks may have already taken place. The militant group's leader, Mullah Sayed Mohammad Akbar Agha, has said previously that negotiations with a "tajir" - an influential trader with wide contacts - were continuing.
The crisis is an immediate challenge for Mr Hamid Karzai, who on Wednesday was officially declared the winner of Afghanistan's October 9th presidential election after an independent review panel concluded voting irregularities did not affect the outcome.