United Nations Secretary-General Antonio Guterres said on Friday that a peace agreement in South Sudan was in a shambles, telling the country's leaders to put down the weapons and put all the people of South Sudan first.

Riek Machar, South Sudan's First Vice President and President Salva Kiir's enduring rival, was arrested on Wednesday on "unclear charges", marking a dramatic escalation to a weeks-long conflict

Barrel bombs believed to contain a highly flammable liquid have been used in airstrikes in South Sudan as escalating violence pushes the world's newest country to the brink of another civil war, the UN has said.