Militants claiming to hold three U.N. hostages said Thursday that talks on their demands, including the release of Taliban prisoners, had broken down, and they would decide Friday whether to kill the trio.

The Jaish-al Muslimeen, a shadowy Taliban (search) splinter group, told The Associated Press that Irish-British hostage Annetta Flanigan was "seriously ill" because of the strain of her captivity, and all three were sickened by a diet of little more than cookies.

A purported commander for the group said U.N. and Afghan officials contacted them by telephone Thursday but were "not ready for negotiations."

"We have decided that we won't negotiate any more, either, because they are not making a serious effort to get the hostages released," a man identifying himself as Sadir Momin said in a satellite telephone call.

"Tomorrow we will hold another shura (council) ... Then we will decide whether to kill them or allow more time."

AP reporters in Afghanistan and Pakistan spoke with three purported representatives of the militant group Thursday. Their claims could not be verified independently.

Afghan and U.N. officials were either unavailable or declined to comment. None have confirmed any contact with the kidnappers.

Armed men abducted Flanigan, Filipino Angelito Nayan and Shqipe Hebibi of Kosovo a week ago in the Afghan capital.

The group's leader, Akbar Agha, said in a separate phone call that Flanigan was ailing.

"My friends have told me she is very frightened. She can't speak smoothly," he said. "The Afghan government will be responsible if anything happens to her."

The abductions were the first kidnappings of foreigners in Kabul since the Taliban was ousted in 2001 and sparked concern militants were copying the tactics of their Iraqi counterparts.

The group released a videotape of the hostages Sunday to back its claim of responsibility and has demanded the withdrawals of British troops and the United Nations from Afghanistan in return for the hostages' lives.

Still, Afghan officials doubt the little-known group could have pulled off the kidnappings without the help of a local militia or criminal gang, and authorities have conducted a number of searches in and around the city.

On Thursday, the group claimed it gave authorities a list of 25 Taliban prisoners, some held at a U.S. military prison in Guantanamo Bay (search), Cuba, and others in Afghan jails.

"The government said they would think about releasing those Taliban held in Afghan prisons and discuss the prisoners held by the Americans," spokesman Syed Khaled said.

U.N. spokesman Manoel de Almeida e Silva thanked the Afghan government Thursday for its efforts to free the hostages. He said the world body was "doing all it can" in support, but he gave no details.

He also said U.N. staff had received messages of support, including a statement by the Council of Ulema, or religious scholars, which said the kidnappings "defame Islam."

"However, we are increasingly worried about Shqipe, Lito and Annetta," Almeida e Silva said. "The psychological pressure must be tremendous, not knowing what will happen from one day to the next ... We ask those holding them to release them immediately and unharmed."

The militants have backed off a series of deadlines to kill the three hostages, claiming negotiations are under way. They also have suggested that Nayan, a Philippine diplomat, might be spared because his country has no troops in Afghanistan.

All three hostages were helping manage Afghanistan's Oct. 9 presidential election.

The hostage-taking cast a shadow over the official announcement on Wednesday that U.S.-backed Hamid Karzai (search) was Afghanistan's first-ever popularly elected president.

"It has saddened all the electoral staff and the nation of Afghanistan," electoral board chairman Zakim Shah said, appealing for the swift release of the victims "to put an end to this suffering during what should be a time of national celebration."