Sudan's president has named a politician from Darfur, Adam Youssef, as his vice-president, the state-run Suna news agency says.One of Sudan's two vice-presidency roles became vacant in July when Salva Kiir gave up the position to lead newly independent South Sudan.Mr Youssef comes from one of Darfur's Arab ethnic groups and recently joined President Omar al-Bashir's party.Mr Bashir denies accusations of war crimes in the western Darfur region.The UN says some 300,000 people have died during Darfur's eight-year conflict between black African rebel groups and Arab militias in Darfur.The government says this figure has been exaggerated and the true figure of deaths from the conflict is 12,000. 'No different'Some rebel groups in Darfur have rejected the appointment of Mr Youssef as symbolic."He is part of the Arabisation of Darfur. He won't make a difference," el-Tahir el-Faki, a senior official in the Justice and Equality Movement (Jem) told Reuters news agency.Jem and another rebel group the Sudan Liberation Army have rejected a recent peace deal signed between Khartoum and the Liberation and Justice Movement (LJM) - an umbrella group of rebel factions.Jem signed a ceasefire with the Sudanese government in February 2010 but abandoned peace talks soon after, accusing Khartoum's forces of launching new raids in Darfur.Mr Youssef was an Islamist and leading figure in the opposition Popular Congress Party until November 2010, Sudan's Tribune newspaper reports.The International Criminal Court has issued an arrest warrant for Mr Bashir and other officials, accusing them of genocide and crimes against humanity in Darfur.