U.S. Navy Secretary Gordon England visited this American naval base Wednesday to observe panels aimed at reviewing the cases of hundreds of prisoners accused of links to Afghanistan's ousted Taliban rulers or the al-Qaida terror network. His visit came as the military acknowledged that four detainees have refused to appear before the panels, known as Combatant Status Review Tribunals, which are to determine whether each detainee is properly held as an «enemy combatant» or should be released. The first detainees to appear aren't charged and have been at Guantanamo for two to two and a half years, officials said. A seventh case was heard Wednesday, and England was to attend an eighth in the afternoon. Recommendations by the three-member military review tribunals have yet to be announced. All of the approximately 585 detainees have been deemed «enemy combatants» and not prisoners of war under the Geneva Conventions, which would grant them additional legal rights. The military announced review tribunals after the U.S. Supreme Court ruled in June that prisoners have a right to challenge their detention in U.S. courts. They are separate from military commissions that are being set up to try at least four detainees, starting with pretrial hearings planned in late August.