UPDATE 4-Over 99 percent of south Sudan votes to separate, Posted by Meosha Eaton

* First official announcement confirms early reports
* Southern leader hails Sudan's president as "champion"
* Independence to take effect on July 9 (Adds details on overall vote)

By Jason Benham and Jeremy Clarke JUBA, Sudan, Jan 30 (Reuters) -

South Sudan overwhelmingly voted to split from the north in a referendum intended to end decades of civil war, officials said on Sunday, sparking mass celebrations in the southern capital Juba. Thousands cheered, danced and ululated after officials said 99.57 percent of voters from the south's 10 states chose to secede, according to the first official preliminary results. "This is what we voted for, so that people can be free in their own country ... I say congratulations a million times," south Sudan's president Salva Kiir told the crowd.

The vote was promised in a 2005 peace deal which ended decades of north-south conflict, Africa's longest civil war which cost an estimated 2 million lives. Kiir, the head of the former southern rebel Sudan People's Liberation Movement (SPLM), praised his former civil war foe, Sudan's overall president Omar Hassan al-Bashir, for agreeing to the 2005 accord. "Omar al-Bashir took the bold decision to bring peace. Bashir is a champion and we must stand with him," said Kiir, speaking in a mixture of English and the local Arabic dialect. "The project has not finished ... We can not declare independence today. Let us respect the agreement. We must go slowly so we can reach safely to where we are going," he added.

According to the terms of the accord, south Sudan will be able to declare independence on July 9, pending any legal challenges to the results. UNRESOLVED ISSUES Leaders from the SPLM and Bashir's northern National Congress Party (NCP) still have to agree on a list of politically sensitive issues, including the position of their shared border, how they would split oil revenues after secession and the ownership of the disputed Abyei region. "I am so happy. Imagine having schools, no fear, no war. Imagine feeling like any other people in their own country. At least now we feel this is our own land," student Santino Anei, 19, told Reuters. U.N. Secretary General Ban Ki-moon praised north and south Sudan for the peaceful vote but said he was concerned about the unresolved issues. "Peace in north and south Sudan will require statesmanship and patience," he said addressing an African Union summit in Addis Ababa.

Secession campaigners described the vote as a chance to end years of perceived northern exploitation. Bashir, who campaigned for unity, later announced he would accept the widely-expected separation vote. Chan Reek Madut, the deputy head of the commission told the crowd the south had voted 99.57 percent for separation. He later told Reuters the results for the entire vote including southerners in north Sudan and eight other countries -- the U.S. Australia, Egypt, Uganda, Kenya, Ethiopia, Canada and Britain --, would be calculated and released early in February.

The commission's website reported on Sunday the overall vote was 98.83 percent, but added that this could change. Five of the 10 states in Sudan's oil-producing south showed a 99.9 percent vote for separation and the lowest vote was 95.5 percent in favour in the western state of Bahr al-Ghazal which borders north Sudan.

(Additional reporting by Richard Lough in Addis Ababa; Writing by Andrew Heavens; Editing by Matthew Jones)