KABUL — US Secretary of State John Kerry flew into Afghanistan on an unannounced visit Monday to see President Hamid Karzai amid concerns the Afghan president may be jeopardizing progress in the war against extremism with his anti-American rhetoric. He arrived shortly after the US military ceded control of its last detention facility in Afghanistan, ending a longstanding irritant in relations. Kerry arrived in the Afghan capital for a 24-hour visit, during which he met Karzai, civic leaders and others to discuss continued US assistance to the country and how to wean it from such aid as the international military operation winds down, and upcoming national elections. Karzai has infuriated US officials by accusing Washington of colluding with Taliban insurgents to keep Afghanistan weak even as the Obama administration presses ahead with plans to hand off security responsibility to Afghan forces and end NATO's combat mission by the end of next year. US officials accompanying Kerry said he did not lecture Karzai or dwell on the apparent animosity but made clear once again that the US did not take such allegations lightly. He said he pressed Karzai on the need for May's elections to meet international standards and continue to stress the importance of Afghan reconciliation and US support for a Taliban office in Qatar where talks could occur. Earlier Monday, the US military ceded control of the Parwan last detention facility near the US-run Bagram military base north of Kabul, a year after the two sides initially agreed on the transfer. Karzai demanded control of Parwan as a matter of national sovereignty. The top US commander in Afghanistan, Gen. Joseph Dunford, handed over Parwan at a ceremony there after signing an agreement with Afghan Defense Minister Bismullah Khan Mohammadi. “This ceremony highlights an increasingly confident, capable and sovereign Afghanistan,” Dunford said. The dispute over the center threw a pall over the ongoing negotiations for a bilateral security agreement that would govern the presence of US forces in Afghanistan after 2014. An initial agreement to hand over Parwan was signed a year ago, but efforts to follow through on it constantly stumbled over American concerns that the Afghan government would release prisoners that it considered dangerous. A key hurdle was a ruling by an Afghan judicial panel holding that administrative detention, the practice of holding someone without formal charges, violated the country's laws. The US argued that international law allowed administrative detentions and also argued that it could not risk the passage of some high-value detainees to the notoriously corrupt Afghan court system. An initial deadline for the full handover passed last September and another earlier this month. The detention center houses about 3,000 prisoners and the majority are already under Afghan control. The United States had not handed over about 100, and some of those under American authority do not have the right to a trial because the US considers them part of an ongoing conflict. There are also about three dozen non-Afghan detainees, including Pakistanis and other nationals that will remain in American hands. The exact number and nationality of those detainees has never been made public. A new agreement, or memorandum of understanding, was signed at the ceremony by Dunford and Khan, but the US military said it will not be made public. The agreement supplants one signed last March, which had been made public. The US military said in a statement that the new agreement “affirms their mutual commitment to the lawful and humane treatment of detainees and their intention to protect the people of Afghanistan and coalition forces,” an apparent reference to the release of detainees deemed to be dangerous. The US started to hold detainees at Bagram Air Field in early 2002. For several years, prisoners were kept at a former Soviet aircraft machine plant converted into a lockup. In 2009, the US opened a new detention facility next door. The number of detainees incarcerated at that prison, renamed the Parwan Detention Facility, went from about 1,100 in September 2010 to more than 3,000. After Monday's handover, it was renamed the Afghan National Detention Facility at Parwan and the US military said it would provide the Afghan army with advisers and $39 million in funding. The United States has spent about a quarter of a billion dollars to build the Bagram facility along with Kabul's main prison located in the capital. — AP