South Sudan troops seize Bentiu
4 May 2014 Last updated at 15:46 BST
Government forces appear to have taken control of the rebel-held town of Bentiu after opening fire on the enemy positions.
The BBC's Alastair Leithead was at the UN base on the edge of the town and saw troops and militia march towards Bentiu.
The oil-rich town was captured by rebels last month.
On Friday the US Secretary of state John Kerry said peace talks aimed at ending the violence between the two largest ethnic groups had been agreed.