In February 1991, a national conference began; the opposition gained control of the conference, and the conference's declaration of its own sovereignty was not challenged by Sassou Nguesso. The conference, which concluded in June 1991, chose André Milongo as prime minister during the transitional period leading to scheduled elections in 1992. Milongo was given executive powers, leaving Sassou Nguesso as effectively a figurehead president. Sassou Nguesso's power was so limited by the Conference that he was barred from travelling outside of Congo without the transitional government's approval. He was also subjected to serious criticism and allegations during the Conference, including a claim from some delegates that he was involved in Ngouabi's 1977 assassination. His eventual response to the criticism on 26 April was "repentant rather than defiant" in tone.