KHARTOUM Sudan's northern army seized control of the disputed, oil-producing Abyei region, officials said on Sunday, forcing thousands to flee and bringing the country's north and south to the brink of full conflict.
Khartoum sent tanks into Abyei town, the area's main settlement, on Saturday, the United Nations said after weeks of growing tension and accusations of skirmishes by both sides.
Analysts fear northern and southern fighting over Abyei could reignite a full blown war in Sudan, a development that could have a devastating impact on its neighbours which include Kenya, Uganda and Ethiopia.
Both the United States and Britain condemned the escalation of violence in the fertile border region.
Control over Abyei remains the biggest point of contention in the countdown to the secession of south Sudan, expected in July.
U.N. officials said the north had sent at least 15 tanks into Abyei town.
"Most residents in Abyei town left yesterday (Saturday) and have gone south. There are reports of looting by armed groups," U.N. spokeswoman Hua Jiang told Reuters, adding the town's population was estimated at around 20,000.
Southerners overwhelmingly voted to declare independence from the north in a January referendum, promised in the 2005 peace deal that ended the last north-south civil war.
That conflict between the mainly Muslim north and the south, where most people follow Christian and traditional beliefs, killed an estimated 2 million people.
Analysts said there was a risk that a new north-south war could have an equally serious impact and fighting could spread over Sudan's borders disrupting some of east Africa's most promising economies.
HAZARDS FOR NEIGHBOURS
In the previous war, countries bordering Sudan were flooded with refugees during the fighting. Khartoum was also accused of arming militias, including Uganda's rebel Lord's Resistance Army, to destabilise the south.
The north denied the allegations.
North Sudan said it had sent its troops to Abyei to clear out southern soldiers that it said had entered the area, breaking the terms of earlier agreements.
"The Sudanese armed forces control Abyei and are cleansing it of illegal forces," Amin Hassan Omar, a minister of state for presidential affairs, told reporters after meeting a delegation of the U.N. Security Council in Khartoum.
The southern army (SPLA) accused the north of shelling villages and said it had withdrawn its forces from Abyei town after the north moved in.
"We call on the United Nations to protect civilians," said southern army (SPLA) spokesman Philip Aguer. "We are worried about our troops. Communications are poor. We cannot get through to them."
The White House condemned the north's military operations in Abyei as "disproportionate and irresponsible" and urged northern and southern leaders to meet and negotiate a settlement.
Britain's Foreign Secretary William Hague condemned the attack on Abyei town, and an earlier ambush that was blamed on southern soldiers.
"I call on all sides to cease hostilities immediately. All unauthorised forces should be withdrawn from the entire area of Abyei," Hague said in a statement.
The 2005 peace deal promised Abyei residents their own referendum over whether they wanted to join the north or the south. But that vote never took place after both sides failed to agree over who was qualified to vote.
Attempts to agree Abyei's status through negotiations have also stalled.
The north supports the Arab Misseriya tribe that grazes its cattle for parts of the year in Abyei, while the south has strong links to the Dinka Ngok tribe that lives there all year round.
(Reporting by Ulf Laessing; editing by Andrew Heavens)