MAHAMAT RAMADANE CHAD's interior ministry says it has arrested several people after uncovering a plot to assassinate prominent political figures and bomb polling stations and the electoral commission headquarters ahead of Sunday's presidential election. Politicians were among those arrested for planning the killings of opposition and civil society leaders in an attempt to frame the government, the ministry said in a statement late on Thursday. Rights groups and opposition politicians say authorities have cracked down on dissent ahead of Sunday's vote when Chad's President Idriss Deby is poised to extend his three-decade rule. One presidential candidate Yaya Dillo has been…