The Bicesse Accords, also known as the Estoril Accords, laid out a transition to multi-party democracy in Angola under the supervision of the United Nations' UNAVEM II mission. President José Eduardo dos Santos of the MPLA and Jonas Savimbi of UNITA signed the accord in Lisbon, Portugal on May 31, 1991. UNITA rejected the official results of the 1992 presidential election as rigged and renewed their guerrilla war.