* Voters lists finalised by Dec 31, Jan 9 deadline
* Unforeseen events may delay referendum (Adds U.S. State Department comment)
By Andrew Heavens
KHARTOUM, Oct 5 (Reuters) - Sudanese officials on Tuesday announced a long-awaited timetable for a referendum on the independence of the oil-producing south, but warned unforeseen circumstances could still delay the vote.
Southerners were promised a chance to vote on whether to stay in Sudan or secede in a 2005 peace deal that ended decades of civil war with the north.
Preparations for the vote, scheduled for Jan. 9, 2011, are already well behind schedule and southerners have accused the north of trying to delay the poll to keep control of the region's oil, a charge Khartoum denies.
South Sudan president Salva Kiir on Friday said all signs now pointed to southerners choosing independence and there was a risk of "a return to violence on a massive scale" if the vote was disrupted or delayed.
According to the timetable, voter registration should start mid November, with the final voter list ready by Dec. 31, leaving just eight days before the Jan. 9 deadline, referendum commission member Chan Reek Madut told Reuters.
"The timetable has come out. It has been agreed upon ... The dates, the periods for objections, for amendments (to the registration list) have all been condensed to make sure the final voter registration comes out around the 31st of December," he said.
"We don't want anyone to tamper with the 9th January date. Everybody is focused on that date."
Voter registration would end on Dec. 4 and parties would be allowed to start campaigning for their preferred outcome on Dec. 7, Madut added.
He said plans to identify voting stations and referendum staff were on track in the south, but he was less sure on work to register southern voters living in the north and outside Sudan in the diaspora.
TIGHT TIMING
Madut said the timing was now very tight and it was possible unforeseen circumstances could still hold up the vote.
"By that time every one will be registered will have a card in his or her hand. Then they would understand the practical reasons for any delay."
Political tensions are mounting around a second vote promised in the 2005 accord -- a referendum on whether the central oil-producing region of Abyei should join the south or the north.
That vote is also supposed to take place on Jan. 9, 2011, but northern and southern leaders are still wrangling over who should be allowed to vote, and have not even agreed on the members of a commission to organise the process.
Sudan vice president Ali Osman Taha, a member of the north's National Congress Party, on Monday warned the vote would not go ahead without a deal.
Northern and southern leaders have been meeting in Addis Ababa since late Sunday to try to hammer out an arrangement.
U.S. State Department spokesman P.J. Crowley said the Abyei talks in Addis Ababa were likely to continue on Wednesday.
"They have been in very, very direct talks, frank talks. The parties did not agree on every detail but we certainly believe that an agreement on Abyei is possible," Crowley said.
"Whether they can get there or not we'll see, but we remain deeply engaged in this," he said.
Crowley said the United States still hoped that Sudan could successfully hold the two referendums in January despite the large amount of preparatory work ahead.
"We believe that this can still occur on time and be successful if the parties make decisions and then act quickly," he said.
(Reporting by Andrew Heavens, additional reporting by Barry Malone in Addis Ababa and Andy Quinn in Washington)
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