The Sudanese government is to sign a peace deal with the southern rebels on Sunday, with an aim to end Africa's longest-running civil war. The much awaited peace agreement between Khartoum and the rebel Sudan Popular Liberation Movement (SPLM) has prompted fresh calls from the United States for renewed bid to bring peace even in the country's western Darfur region. Sunday's signing ceremony will be attended by US Secretary of State Colin Powell, several African leaders and delegates from Arab and European nations. "We can't overlook that while we are celebrating tomorrow the achievement in north-south dialogue, we continue to have the difficult, terrible conflict in Darfur," Powell said. Powell said sanctions were an option for the United Nations in its efforts to end Darfur's "terrible conflict" but he refused to repeat his earlier charge that genocide was taking place in the western region. "The UN still has options before it, to include sanctions, and we do not take any of those options off the table," he said. **Peace precursor*** Diplomats say Sunday's north-south peace deal may be the model for Darfur where the crisis has uprooted more than 1.6 million people. The southern civil war between government forces and the SPLM rebel army began in 1983. The fighting killed about two million people and forced millions more from their homes. The conflict in Darfur has been no less bloody. The crisis was triggered in February 2003 when rebel groups took up arms against the government in a struggle over power and scarce resources. **PHOTO CAPTION*** U.S. Secretary of State Colin Powell (L) shakes hands with Sudan's First Vice President Ali Osman Mohamed Taha(R) as rebel John Garang (C) of the Sudan's Peoples Liberation Movement walks behind them in Nairobi, January 8, 2005. (Reuters)