The resolution adopted unanimously today by the UN's most powerful body will also increase the UN's international police contingent from 900 to 1,323.
To reach the new levels, the council authorised the temporary transfer of troops, police and equipment from UN missions in Congo, Darfur, Abyei, Ivory Coast and Liberia. The UN also wants attack helicopters for South Sudan.
The council condemned the fighting and violence against civilians and ethnic communities that have caused hundreds of deaths across South Sudan, and reported human rights violations by all parties.
It called for "an immediate cessation of hostilities and the immediate opening of a dialogue".
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