Southern Sudan's minister of defense and a presidential adviser were among at least 23 people killed on Friday in a plane crash blamed on engine failure, officials said. Dominic Dim, the south's defense minister and minister of SPLA affairs, and Justin Yak, a presidential adviser for local government affairs, were on the plane that crashed near the southern town of Rumbek, the officials said. Deng Goc, a spokesman for the Southern People's Liberation Movement (SPLM), confirmed that Dim had been on the plane but could not confirm if Dim had died. “Twenty-one passengers were killed and either two or three crew members,” First Vice President Salva Kiir told a news conference. “Two engines failed and there was nothing the pilot could do.” Yak's wife was also among the dead, said a southern government official. The former southern rebel SPLM signed a 2005 accord with the northern National Congress Party (NCP), ending Africa's longest civil war. The accident comes a day after southern army officials said Sudan's northern and southern forces had agreed to withdraw from a border flashpoint where clashes in the last month have killed dozens. The clashes in Unity state, near one of Sudan's largest oil fields, could disrupt a 2005 north-south peace deal that ended Africa's longest civil war. The UN said the plane was a Beechcraft 1900 operated by South Sudan Air Connection traveling from Wau to Juba with 21 passengers on board. The United Nations said it had sent a helicopter to the crash site. The plane had been rented from a charter company and was carrying a delegation of leaders from the (former rebel) Sudan People's Liberation Movement from Wau to the capital. Southern rebel leader John Garang died in July 2005 when the Ugandan presidential helicopter he was traveling in crashed in southern Sudan, with some suspecting foul play.