Juba: Southern Sudanese began voting on Sunday in a week-long independence referendum expected to lead to the partition of Africa`s largest nation and the creation of the world`s 193rd UN member state.
South Sudanese president Salva Kiir proclaimed the event an "historic moment" for his people as he was among the first to cast his ballot in the regional capital Juba when polling stations opened at 8:00 am (0500 GMT).
Thousands of jubilant south Sudanese had queued through the night to be among the first to have their say on whether the impoverished south should finally break away from rule by Khartoum.
"This is the historic moment the people of south Sudan have been waiting for," Kiir said, holding up his hand to reporters to show the indelible ink that demonstrated he had voted.
US envoys Scott Gration and John Kerry as well as Hollywood star George Clooney watched as he cast his ballot at a polling station set up at the memorial to late rebel leader John Garang in the regional capital Juba.
"I would like to call on all south Sudanese people to be patient in case anyone does not have time to cast his or her vote today," Kiir said.
Polls were due to close at 5:00 pm (1400 GMT) on the first day of the seven-day independence referendum that is the centrepiece of a 2005 north-south peace deal that ended Africa`s longest-running conflict.
Kerry, who along with Gration had engaged in intensive shuttle diplomacy for months to clear the way for the momentous vote, said after watching Kiir cast his vote that the referendum represented a "new chapter" for Sudan.
Clooney, who has long campaigned passionately for Sudan, described the launch of the referendum as a "great day for all the world”.
Euphoria gripped Juba as people feted the looming end of a long and often difficult countdown.
Yar Mayon, who grew up in refugee camps in Ethiopia and Kenya, said: "I came here in the early morning because I wanted to show just how much I wanted to vote.”
"It was so important to me I could not sleep," she said, as she prepared to cast her ballot.
As the sun rose, another voter, Wilson Santino said: "This is a new dawn because we vote for our freedom.”
"We have been fighting for too many years but today this vote for separation is also for peace. Soon the sun will be shining over a free south Sudan."
But the celebrations were overshadowed by deadly clashes with armed tribesmen and renegade militiamen in two remote oil-producing districts on the north-south border that were bitterly contested in the 1983-2005 civil war.
Kiir told his people in an eve of polling day message that there was no alternative to peaceful coexistence with the north.
"Fellow compatriots, we are left only with a few hours to make the most vital and extremely important decision of our lifetime," he said.
"The referendum is not the end of the journey but rather the beginning of a new one," he added, alluding to the six-month transitional period to recognition as an independent state stipulated by the 2005 peace agreement.
US envoys had led an intensive international diplomatic effort right up to the last minute to ensure that the referendum went ahead as scheduled. Gration alone made 24 trips to the region.
Sudanese President Omar al-Bashir, an Army man who led the north`s war effort against the south for a decade and a half before signing the 2005 peace deal, has said he will respect the outcome of the vote if it is "free and transparent”.
US President Barack Obama, in an opinion article published by the New York Times on Saturday, said voters must be allowed to make their choice free from intimidation and coercion.
If the Khartoum government lived up to its obligations under the 2005 peace deal and respected the outcome of the vote, Obama said, it could be removed from a US list of state sponsors of terrorism.
"Today, I am repeating my offer to Sudan`s leaders -- if you fulfil your obligations and choose peace, there is a path to normal relations with the United States," he wrote.
Aides say that Obama, grounded in a commitment to Africa, from where he traces part of his lineage, left administration officials in no doubt of the grave stakes posed by Sudan`s potential split.
"Let me be clear about what this means to me," one official quoted Obama as saying during a staff meeting earlier this year.
"Two million people died the last time there was a conflict between north and south. That cannot happen again."
The conflict between the Muslim, mainly Arab north, and the African, mainly Christian south, has blighted Sudan virtually since independence from Britain in 1956, fuelled by religion, ethnicity, ideology and resources, particularly oil.