The presidential candidate of the Sudan People's Liberation Movement, which governs the semi-autonomous region of Southern Sudan, said he's withdrawing from next month's election, the first multiparty vote in 24 years. Yasser Arman cited 'many violations' in preparations for the presidential vote, especially in the western region of Darfur, where government forces and insurgents have battled for the past seven years. 'The security conditions do not allow for free and fair elections to be held in Darfur,' Arman told reporters in the capital of Khartoum. 'Therefore I will not participate in the presidential elections.' While the SPLM as a party will run in the elections across the rest of Sudan, it is withdrawing its candidates in Darfur, he said. The April 11-13 vote for the presidency, parliament and state governorships will take place five years after the SPLM signed a peace deal with the government, ending a 20-year civil war between the Muslim north and the south, where Christianity and traditional religion dominate. Southern Sudan will vote in a referendum in January to decide whether to secede from the rest of Sudan, sub- Saharan Africa's third-biggest oil producer. A coalition of opposition parties in northern Sudan on Wednesday postponed a decision on whether to boycott the vote. It accuses the government of rigging the election and says the National Elections Commission is biased in favor of Umar al-Bashir's National Congress Party. The International Crisis Group also accused Bashir's government of rigging the election. The government has 'manipulated the 2008 census, drafted the election laws in its favor, gerrymandered electoral districts, co-opted traditional leaders and bought tribal loyalties,' Brussels-based ICG, a private nonprofit group that works to prevent conflict, said Tuesday in a report. 'The legal environment for free and fair elections does not exist,' Fouad Hikmat, Crisis Group's special adviser on Sudan, said in the report. 'The international community should acknowledge that whoever wins will lack legitimacy.' The government rejected the charges. 'These accusations are not true and have no basis,' Rabie Abel Ati, adviser to the minister of information, said Tuesday by phone from Khartoum. 'The registered voters will come and vote in front of international observers and in front of everyone to see.' The U.S., Britain and Norway on Wednesday called on Sudan's government and political parties to address allegations of intimidation, harassment and other safety concerns to clear the way for the vote. 'We urge all parties in Sudan to work urgently to ensure that elections can proceed peacefully and credibly in April,' the countries said in an e-mailed statement. While rigging has occurred across Sudan, Crisis Group said, the focus has been on Darfur, where as many as 300,000 people have died, mainly of disease and starvation, and almost 10 times that number have been displaced by the conflict, according to United Nations estimates. The government puts the death toll at about 10,000. 'Winning big in Darfur is central to the NCP's plan to capture enough votes in the north to ensure its continued national dominance,' according to the Crisis Group report. Bashir, who has ruled Sudan since coming to power in a military coup in 1989, has been indicted by the International Criminal Court on charges he was responsible for war crimes and crimes against humanity in Darfur. Crisis Group called on international observers, such as the Atlanta-based center founded by former President Jimmy Carter and his wife, Rosalynn, the European Union and the African Union, to document 'the severely flawed process.' With assistance from Alan Boswell in Juba and Nicole Gaouette in Washington. 