Clashes between south Sudan's army and armed northern nomads killed 13 in the latest flare-up in the oil-producing border region, escalating tensions ahead of April elections, an army spokesman said.
   
Southerners will also vote in a January 2011 referendum on secession from Sudan's north, which they accuse of oppression after a civil war that has raged on and off for more than five decades. Many analysts believe the vote will create Africa's newest nation state.
       
The attack on the oil-producing Unity state which produces Sudan's light Nile Blend happened on Wednesday, Kuol said.
   
Sudan's north and south have not agreed on key issues ahead of the 2011 referendum, including defining their common border, citizenship and the rights of communities whose livelihoods traverse the frontier.
   
Kuol said there were political motives behind the attacks. Misseriya graze their cattle to the south of the border. The south says the north armed some members of the tribe as a proxy militia during the war.
   
The south's semi-autonomous government says the nomads are welcome but must leave weapons in the north. Herders say this leaves them vulnerable to wild animals and cattle raiders.
   
An agreement signed earlier this year between the herders and southern officials says that the nomads may now bring in five small guns to accompany large herds and three guns if they are moving with smaller groups.
   
But Kuol says the nomads were breaking this agreement and carrying too many guns.

Source: Reuters