GENEVA — The United States came under heavy scrutiny Wednesday from U.N. experts investigating whether it had violated the terms of a global treaty that prohibits torture.

The panel quizzed Obama administration officials not just on the treatment of suspected terrorists held at CIA so-called “black sites” during the administration of President George W. Bush, but also the practices of U.S. police officers and prison guards. Among the topics were prolonged solitary confinement in prisons and the sexual abuse of inmates.

Mary E. McLeod, the acting legal adviser to the U.S. State Department, acknowledged that in the wake of the Sept. 11, 2001, attacks, “We did not always live up to our own values, including those reflected in the convention,” a reference to the 1984 U.N. Convention against Torture, which the United States and 155 other nations have signed.

The session was part of the periodic review of U.S. compliance with the anti-torture convention. The U.S. was last reviewed in May 2006.

U.S. officials are expected to respond Thursday to questions from the 10-member panel on whether the United States has a “specific plan and timetable” for closing the detention center for suspected terrorists at Guantanamo Bay, Cuba, and whether the United States intends to release 28 videos of the forced feeding of Guantanamo prisoners on a hunger strike. A federal court has ordered the administration to make the videos public. The panel also wants to know why the U.S. has refused to allow the U.N.’s special rapporteur on torture to meet privately with detainees at Guantanamo.