The head of the delegation, Abdul Jabar Sabhet of the Interior Ministry, said the delegation was given the chance to speak freely with all 96 Afghan prisoners about their living conditions. Sabhet said there were "only one or two" complaints.
"Conditions of the jail was humane. There were rumors in this country about that. It was wrong. What we have seen was OK," he said.
Sabhet's assessment comes five days after the suicides of three detainees at the Guantanamo Bay prison in Cuba.
He said more than half of the Afghan prisoners were expected to be transferred soon, though he didn't have an exact date.
"We ensure the Afghan people that Afghan prisoners will soon return to our country," he said.
Last August, the United States and the Afghan government announced an agreement to send Afghans held at the detention center and elsewhere back to their country. No date was specified at the time.
Those expected to be released soon were accused of less serious crimes, Sabhet said.
American and allied Afghan forces captured thousands of suspected Taliban and al-Qaida members in Afghanistan after a U.S.-led invasion toppled the repressive Taliban government in late 2001.
Hundreds of detainees were classified as "enemy combatants" and transferred to Guantanamo. Many have since been returned home.
The three suicides Saturday were the first detainee deaths at Guantanamo — where the U.S. holds about 460 men on suspicion of links to al-Qaida or the Taliban — and the military said they have prompted a complete review of operations at the detention center.
The Center for Constitutional Rights has called on the military to allow an emergency independent inspection of the base to confirm the causes of death of the three detainees and to provide an assessment of the health of the other prisoners.