Addis Ababa - UN Secretary General Ban Ki-moon called Saturday for  national unity in Sudan and ruled out deploying UN peacekeepers in Somalia, on  the eve of an African Union summit.

African leaders are officially gathering in Addis Ababa for three days of talks  on information technology, but escalating violence in Somalia and the looming  risk of secession by south Sudan are set to dominate the summit.

Ban said the coming 12 months would be crucial for Sudan, with elections planned  for April - the troubled African country's first multi-party ballot since 1986 -  and a referendum on independence to be held in January 2011.

In a joint interview with AFP and RFI radio, the UN chief said the United  Nations and the African Union had a duty to work for national unity in Sudan and  avoid the south seceding.

"The UN has a big responsibility with the AU to maintain peace in Sudan and make  unity attractive," he said.

Sudan's mainly Muslim north and largely Christian south ended 21 years of civil  war in January 2005.

The Comprehensive Peace Accord (CPA), as the deal is known, allowed the creation  of a semi-autonomous government for the south and paved the way for April's  presidential, parliamentary and regional polls, and next year's referendum.