Kabul, Afghanistan (CNN) -- Afghan President Hamid Karzai is calling the United States' refusal to hand over an undisclosed number of detainees a breach of an agreement that outlines the transfer of power from U.S. forces to Afghanistan.
Karzai's accusation comes two months after the United States handed over Parwan prison at Bagram Air Base. The handover of the prison and detainees was considered the linchpin in a larger agreement that spells out U.S.-Afghan relations following the withdrawal of American troops in 2014.
In a statement released Monday, Karzai called the failure to hand over all the detainees "a serious breach of the Memorandum of Understanding." He ordered his defense minister, attorney general and prison administrator "to take required and urgent measures" to ensure the complete transfer of authority.
The issue has become a sticking point between Karzai and U.S. military leaders. Karzai has been adamant that all prisoners be under Afghan control, and his latest statement indicates a growing frustration with the U.S. military's resistance to surrender the remaining prisoners.
The United States "paused" the transfer of the detainees on the day it handed over Parwan prison in September.
At the time, Karzai called the action a breach of Afghan national sovereignty.
The U.S. military has not publicly discussed the specifics of the dispute. But a military official, speaking on condition of anonymity, told CNN in September that the United States was holding on to several detainees over concerns about whether Afghan authorities will properly handle their cases, and under what circumstances they might be released.
The United States also is maintaining custody of several prisoners whose nationalities were not Afghan, said the military official, who was not authorized to publicly disclose the details.
Roughly 99% percent of the detainees in custody were turned over, the U.S. military has said.
Last year, a loya jirga, or grand assembly of Afghan elders, endorsed the continued presence of U.S. forces following the end of combat operations in 2014, though only if the two countries could agree on the transfer of prisoners, an end to night raids and lifting immunity for U.S. troops accused of committing crimes.
CNN's Chelsea J. Carter and Barbara Starr contributed to this report.