The United Nations envoy to South Sudan cautioned Tuesday that a power-sharing deal set to be signed by President Salva Kiir was only a first step to end the brutal conflict.
The signing is scheduled to take place in Juba on Wednesday with Kiir to be joined by the leaders of Kenya, Uganda, Sudan and Ethiopia for the mini-summit.
South Sudan's rebel leader Riek Machar, a former vice president, already signed the deal on August 17, in line with a deadline to do so.
UN envoy and mission chief Ellen Margrethe Loej told the Security Council that Wednesday's signing would be a "hopefully positive development" but that many hurdles lie ahead to implement the agreement.
"While we will do all possible to support implementation, I must remind this council that, albeit very important, this agreement is only a first step," said Loej.
"Peace, stability and prosperity will not come to South Sudan overnight," she warned.
The world's youngest nation, South Sudan has been torn by fighting between forces loyal to Kiir and rebels allied with Machar since December 2013 and the violence has imploded along ethnic lines.
Loej, who heads the UN peacekeeping mission in South Sudan, said attention must turn to the inter-ethnic fighting which in some states is just as violent as the struggle opposing the two camps.
Her comments reflected concerns about the prospects for the peace deal to take hold after 20 months of war that have fueled one of the world's worst humanitarian crises.
Nearly 70 percent of the country's population is facing food shortages and some 200,000 terrified civilians are sheltering in UN bases.
The UN envoy spoke to the 15-member council amid negotiations on a US draft resolution imposing an arms embargo and targeted sanctions on South Sudan over the failure to sign the peace deal.
Russia, a veto-wielding member of the council, said there would be no need to adopt the resolution if Kiir signs the deal.
"We don't need this resolution if the main purpose is achieved," said Russian Deputy UN Ambassador Petr Iliichev.