DARFUR - At least 50 people were killed in this week's clashes between the South Sudan's army and militias in the town of Malakal, UN officials say.

One UN official said 14 civilians and scores of combatants had been killed, while another put the figure at about 50 people altogether.

The army and a militia previously backed by Khartoum exchanged heavy gunfire in the volatile town.

A 21-year civil war ended in 2005 with a peace deal.

But the two sides remain in dispute about oil-rich areas along the border.

Under the deal, South Sudan enjoys considerable autonomy until a referendum is held in 2011 on whether or not the largely Christian and animist south should secede from the Muslim-dominated north.

The Malakal fighting involved supporters of Gabriel Tang, who was backed by the north during the civil war and is now based in Khartoum.

Fighting between South Sudan's army and elements in the Tang militia killed 150 people in Malakal in 2006.