President Hamid Karzai on Thursday called for the United States to hand over its biggest military prison in Afghanistan within a month, despite repeated warnings that Afghan institutions are woefully unprepared to detain or try suspected terrorists.

Karzai said Afghan government investigators had found violations of the Afghan constitution and international human rights conventions at the prison, which houses about 2,600 inmates near Bagram Airfield. He did not provide details of the alleged violations, but he said in a statement that they constituted a “breach of Afghan sovereignty.”

The transfer of the prison, called the Parwan Detention Center, and its burgeoning population of detainees is regarded by Afghans and Americans as a critical marker in the war’s endgame — a sign that Afghan officials are ready to inherit institutions essential to the nation’s future. U.S. officials said in a public memorandum two years ago that they expected the prison to be transferred in early 2012. Karzai interpreted that timeline as being firm, but U.S. officials point to the document’s caveat that the transfer is subject to “demonstrated capacity.”

The country’s judicial system has remained weak, U.S. officials said, raising concerns that Afghans would be unable to prosecute or detain the many insurgents captured by NATO forces and would allow dangerous Taliban fighters to slip through the cracks. In July, officials told The Washington Post that the United States would be unable to relinquish authority at the prison until at least 2014, when the last foreign troops are scheduled to leave Afghanistan.

“At this point, the Afghans don’t have the legal framework or the capacity to deal with violence being inflicted on the country by the insurgency,” a U.S. official said then. The official spoke on the condition of anonymity because of the matter’s sensitivity.

On Thursday, State Department spokeswoman Victoria Nuland said in response to Karzai’s comments: “We’re going to continue to work with the Afghan government to implement the transition that we have both agreed needs to happen of detention operations in Afghanistan. We need to do this in a manner that is maximally responsible.” She said she could not comment further on the timeline for the transfer.

The existence of the U.S. military prison about 30 miles north of Kabul has long been seen by Afghans as a sign of imperial overreach, and for years Karzai has singled the prison out for criticism. The U.S. military has detained suspected insurgents at facilities in the area for about a decade. Most have been held without trial, and fewer than a third of the detainees have been handed over to an Afghan-run court for prosecution.

Still, the number of Afghan judges and guards has risen steadily, and, as of July, the Afghan-run court at the prison was hearing about 50 cases a month.

Karzai has made bold claims in the name of Afghan sovereignty, and his insistence on a rapid prison transfer ranks among the boldest. But although he craves a more active role for Afghan institutions, he has also made repeated appeals for international support for the country to continue beyond 2014.

A transition at the Bagram prison is expected to hold special symbolic value. Afghan officials say the Taliban has successfully used the prison in propaganda to galvanize insurgents, drawing on reports of harsh interrogation methods. A U.S. Army investigation into the deaths of two detainees in 2002 uncovered evidence that prisoners had been chained to the ceiling by their wrists and severely beaten by guards.

The Pentagon facility was rebuilt in 2009 and the inmate review process was overhauled to increase transparency, officials said.

Staff writer Jason Ukman and staff researcher Julie Tate, both in Washington, contributed to this report.