A ceasefire agreement has come into effect in South Sudan, despite allegations of fresh attacks.
UN deputy spokesman Farhan Haq said there had been "sporadic fighting" in certain areas, some of it after the ceasefire had begun.
The government and rebels signed the ceasefire agreement on Thursday after talks in Ethiopia.
More than 500,000 people have been forced from their homes during the month-long conflict.
Correspondents say that effective monitoring of the truce will be vital, as tension between the two sides is very high.
The talks have now been adjourned and are due to continue on 7 February.
The ceasefire came into effect at about 17:30 GMT on Friday.
Earlier, Brigadier General Lul Ruai Koang, a spokesman for the opposition, accused government forces of attacking rebel positions in Unity state and Jonglei state on Friday.
Military spokesman Colonel Philip Aguer said he was not aware of any new violence, and that clashes had taken place before the ceasefire was signed.
UN Secretary-General Ban Ki-moon said there was a "necessity to continue without delay a national political dialogue to reach a comprehensive peace agreement".
His spokesman, Farhan Haq, said the dialogue should include all political and civil society representatives as well as detainees from the rebel side.
The UN's World Food Programme said on Friday that more than 3,700 tonnes of food, enough to feed 220,000 people for a month, had been stolen from its warehouses during the fighting.
In the past week, government forces have recaptured the two main cities that were under rebel control.
The agreement is thought to address the issue of 11 detainees whom the rebels wanted freed, and whose fate had previously left the talks deadlocked.
The detainees - allies of rebel leader Riek Machar and prominent political figures from a faction of the governing SPLM party - were taken into custody when President Salva Kiir first made the allegations of an attempted coup - which Mr Machar denies.
Although both men have supporters from across South Sudan's ethnic divides, the fighting has often become communal with rebels targeting members of Mr Kiir Dinka ethnic group and soldiers attacking Nuers.
South Sudan is the world's newest state after gaining independence in 2011. It remains one of the least developed countries.