The move eased pressure from the West but raised the dilemma of protecting Abdul Rahman after his release as Islamic clerics have called for him to be killed.
One official said freedom might come as soon as Monday for Rahman, who became a Christian in the 1990s while working for an aid group in neighboring Pakistan.
Muslim extremists, who have demanded death for Rahman as an apostate for rejecting Islam, warned the decision would touch off protests across this religiously conservative country. Some clerics previously vowed to incite Afghans to kill Rahman if he was let go.
Rahman was moved to Kabul's notorious high-security Policharki prison Friday after inmates at a jail in central Kabul threatened him, Policharki's warden, Gen. Shahmir Amirpur, said.
The case set off an outcry in the United States and other nations that helped oust the hard-line Taliban regime in late 2001 and provide aid and military support for Afghan President Hamid Karzai. President Bush and others insisted Afghanistan protect personal beliefs.
Authorities have barred journalists from seeing Rahman. But on Sunday, officials gave AP an exclusive tour of Policharki, which houses some 2,000 inmates, including about 350 Taliban and al-Qaida militants.
Amirpur said Rahman had been asking guards for a "We're going to stand firm for the principle that religious freedom and freedom of religious conscience need to be upheld, and we are hoping for a favorable resolution in this case," Rice said.
The uproar left Karzai in an awkward position. While trying to address concerns of foreign supporters, he also has sought not to alienate religious conservatives who wield considerable influence in Afghanistan.
The court's decision was sure to anger at least some of the clerics who have strongly demanded that authorities enforce a provision in the country's Islamic-based laws calling for the execution of Muslims who abandon the faith.
"There will be big protests across Afghanistan," said Faiez Mohammed, a Sunni Muslim leader in the northern city of Kunduz. "This has shamed Afghanistan in the eyes of other Muslim countries."
A Western diplomat, who spoke on condition of anonymity because of the sensitivity of the issue, said it wasn't clear if the 41-year-old Rahman would be able to stay in Afghanistan or have to move abroad.
A prison official told AP that Rahman had been moved to a new prison Friday because of threats from inmates at his first jail.
Rahman was being prosecuted for converting 16 years ago while working as a medical aid worker for an international Christian group helping Afghan refugees in Pakistan. He was arrested last month after police discovered him with a Bible.
In an interview published Sunday by an Italian newspaper, Rahman said his family, including his former wife and two teenage daughters, reported him to authorities.
He stressed that he was fully aware of his choice to convert.
"If I must die, I will die," Rahman told the Rome daily La Repubblica, which did not interview him directly but channeled questions through a human rights worker who visited him in prison.
Rahman said he chose to become a Christian "in small steps" after leaving Afghanistan around 1990. He moved to Peshawar, Pakistan, then Germany and tried to get a visa in Belgium.
"In Peshawar, I worked for a humanitarian organization. They were Catholics," Rahman said. "I started talking to them about religion, I read the Bible, it opened my heart and my mind."
After saying he was ready to die, he told La Repubblica: "Somebody, a long time ago, did it for all of us," in a clear reference to Jesus Christ.