Ex-foreign minister Mullah Wakil Ahmad Mutawakkil was freed from the US military base in Bagram, Afghanistan after arranging talks between US forces and the Taliban in the southern city of Kandahar, according to a senior Afghan foreign ministry official.
A close friend of Mutawakkil said he was released four days ago.
"Now he is living with his family in Kandahar," he said. "I myself have spoken to him by telephone."
Mutawakkil surrendered to Kandahar authorities in early 2002.
Shortly after that, he was believed to have been transferred to the US headquarters in Afghanistan at Bagram Air Base, just north of the capital Kabul.
He was held without charge or trial.