Sudan's Abyei: 'North-south troop clash' despite deal
South Sudan's army has clashed with northern troops in Abyei, days after a deal to demilitarise the disputed border area, its spokesman has said.
The northern seizure of Abyei town last month sparked fears of renewed conflict ahead of southern independence in July.
Earlier, the south's vice-president told the BBC the north was pursuing a campaign of ethnic cleansing in the adjacent northern South Kordofan state.
Tens of thousands of people have fled fighting there in recent days.
Although South Kordofan is north of what will soon be the international border, it is home to many pro-south communities, especially in the Nuba Mountains, some of whom fought with southern rebels during the war.
Vice-President Riak Machar said the violence was a total violation of the 2005 peace agreement that ended two decades of north-south civil war.
He said he had informed the five permanent members of the UN Security Council of the situation.
"I have spoken to the permanent five, alerting them that what is happening in the Nuba Mountains in Southern Kordofan is ethnic cleansing," Mr Machar told the BBC's Newshour programme.
"It may even degenerate into genocide as happened in Rwanda."
A spokesman for the Sudanese embassy in London, Ibrahim Mubarak, has blamed pro-south militias for instigating the fighting in South Kordofan.
The UN estimates about 60,000 people have been displaced since the fighting began last week.
The violence in South Kordofan broke out shortly after Ahmed Haroun, indicted for alleged war crimes in neighbouring Darfur, was elected governor of the province, defeating the candidate of the SPLM former rebels, who now govern South Sudan.
Each side has accused the other of starting the fighting.
According to the southern army spokesman Philip Aguer, the clashes in neighbouring Abyei broke out at the river Kiir.
UN peacekeepers, inside their fortified compound in Abyei town, were reported to have heard the sounds of artillery fire.
The northern army could not be reached for comment and no details of casualties are available.
The BBC's Peter Martell in the southern capital, Juba, says the latest clash highlights how difficult it will be to reduce tensions on the ground in Abyei despite the deal announced earlier in the week.
After talks in Addis Ababa between Sudanese government officials and representatives of the south, both sides agreed to pull out their troops and replace them with Ethiopian peacekeepers.
But details of the deal have not been made public.
More than 100,000 people fled southwards when the northern troops entered Abyei in May.
Abyei is claimed by a southern group, the Dinka Ngok, and northern nomads, the Misseriya.
Under the 2005 peace deal, Abyei was granted special status and a joint administration was set up in 2008 to run the area until a referendum decided its fate.
That vote was due to take place in January, when the mainly Christian and animist south decided to split from the the largely Arabic-speaking, Muslim north, but has now been postponed indefinitely.
Some 99% of southern voters opted for independence, due to happen on 9 July. Sudan's President Omar al-Bashir said he would accept the verdict of the south, where most of Sudan's oil fields lie.