Sudan’s state security prosecutor has charged the country’s main opposition leader, Sadiq al-Mahdi, with collaborating with rebel groups to overthrow the regime of President Omar al-Bashir, a media network reported Tuesday. Bashir, backed by Islamists, toppled Mahdi’s civilian government in a 1989 coup after which the former prime minister’s Umma Party, Sudan’s main opposition group, has regularly campaigned against the policies of Bashir’s government. “Sudan state security prosecutor has filed a criminal case against Sadiq al-Mahdi for collaborating with rebel groups for overthrowing the regime” of Bashir, said a report published by Sudan Media Centre, a network close to Sudan’s powerful National Intelligence and Security Service (NISS).