Four terrorism suspects charged with killing 76 people in Uganda in 2010 say they were physically abused by F.B.I. agents, an international rights organization reported Tuesday. The suspects said men who identified themselves as F.B.I. agents beat them during interrogations in 2010 and 2011 in Uganda, the Open Society Justice Initiative said in a report. One suspect, Selemi Hijar Nyamandondo, said an interrogator hit him in the eye, causing his glasses to break, his eye to bleed and making him collapse. Omar Awadh Omar said he was punched and slapped by men who said they were F.B.I. agents. An F.B.I. spokesman in Washington called the accusations without merit. “When investigating cases overseas, all F.B.I. personnel operate within the guidelines established by the attorney general as well as all other applicable laws, policies and regulations,” said the spokesman, Paul Bresson.