ADDIS ABABA Ethiopian Prime Minister Meles Zenawi warned of "ghastly" consequences for Africa if Sudan returns to war after a crucial referendum on southern independence in January.
Africa's biggest country is 47 days away from a plebiscite in its oil-producing south on whether to secede or remain part of Sudan -- a vote promised in the 2005 peace deal that ended decades of north-south war.
That conflict, the longest civil war in African history, killed about 2 million people and forced 4 million to flee.
"Like all doomsday scenarios (a return to war) is too ghastly to contemplate," Meles, who hosts crunch Sudan talks in Addis Ababa on Tuesday, told Reuters in an interview.
"That is why we have to use everything in our capacity to stop it from happening because the alternative is massively destructive not only for Sudan or the Horn of Africa, but the continent as whole."
Meles said all-out war was "possible but not inevitable."
Both sides have ramped up their rhetoric, having failed to overcome differences on issues including voter eligibility in the disputed oil-rich Abyei region.
U.N. Secretary-General Ban Ki-moon said last week he hoped to boost the number of peacekeepers in Sudan amid fears the country could be headed for a new civil war.
Leaders from six east African countries -- including Sudanese President Omar Hassan al-Bashir and southern President Salva Kiir -- will attend the meeting in Ethiopia's capital on Tuesday in an attempt to defuse the tension.
However, officials warn there may not be enough time to reach a deal that will please both sides.
"COMPLEX AND DIFFICULT"
Some analysts have drawn parallels between Sudan's situation and that of Ethiopia in 1993 when former province Eritrea held an independence referendum after a group led by Meles and Eritrean leader Isaias Afewerki overthrew a communist regime.
Meles said the Sudanese case was more complex than that of Ethiopia and Eritrea, whose leaders later fell out and went to war in a border conflict that killed 80,000 people.
"There isn't as much trust between the two parties in the Sudan as there was between ourselves and the Eritrean movement," he said. "It is likely to be more complex and more difficult."
Analysts expect most southerners, embittered by decades of war, to choose independence and create Africa's newest country. The north's ruling National Congress Party thinks southerners living in the north might be more open to unity.
Meles -- viewed as an honest broker by both sides -- said neighbouring Ethiopia hoped to stay close to the north and the south, even if a new country were created.
"We have excellent relations with both sides now and there is no reason why we can't maintain these relationships in the future so long, of course, as the doomsday scenario is prevented," Meles said.
(Editing by Giles Elgood)