Ethiopian Prime Minister Hailemariam Desalegn (right) looks on as South Sudan's rebel leader Riek Machar (centre) and South Sudan's President Salva Kiir (left) exchange signed peace agreement documents in Addis Ababa. File picture: Goran Tomasevic

Washington - Washington will impress upon South Sudanese President Salva Kiir the need for an agreement in a new round of peace talks aimed at ending his country's civil war, a top US envoy said Monday.

Donald Booth, the special US envoy for South Sudan, said that message will be delivered in high level talks with Kiir and other regional leaders on the sidelines of a US-Africa summit that opened here Monday.

It comes as a new round of peace talks mediated by the regional bloc IGAD were beginning in Addis Ababa with a famine looming in the east African country.

“We will clearly be delivering messages that it is time to take these negotiations seriously and to move forward on establishing a transitional government and respecting commitments made to date with respect to the cessation of hostilities and access for humanitarian assistance,” he said.

IGAD has set an August 10 deadline for an agreement between Kiir and his former deputy Riek Machar.

The last round of peace talks stalled in June with each side blaming the other for the failure.

Thousands of people have been killed and over 1.5 million have fled more than seven months of fighting between government troops, mutinous soldiers and ragtag militia forces divided by tribe.

Booth warned that famine conditions were expected to be visible by mid-September, adding to the urgency of the situation.

“The South Sudanese really need for these negotiations to succeed,” he said.