Updated

A South Sudanese military spokesman says government troops have captured a rebel stronghold and taken back control of another town, sending rebels fleeing toward the Ethiopian border.

The government offensive comes just days after President Salva Kiir told U.S. Secretary of State John Kerry that he was ready to hold peace talks with rebel leader and former vice president Riek Machar after a peace deal in January failed.

Col. Philip Aguer said Monday government troops have taken over the rebel base of Nasir, in the Upper Nile region, and re-captured Bentiu from rebel control. Aguer says Bentiu was taken after a day-long firefight, with an unknown number of casualties.

South Sudan has been rocked by violence since December, when the president accused the former vice president of staging a coup.