The accident occurred in a remote village in Western Bahr El Ghazal state, north-west of the capital Juba, spokeswoman Linda Tom told Radio Miraya, a station owned and operated by Unmiss.
“As many as 11 children died and one is still receiving medical treatment,” Tom said.
“The scale of this drama is immense, we convey our deepest condolences to the families of the victims,” she added. South Sudan was plunged into a brutal civil war in 2013, two years after achieving independence from Sudan.
The conflict lasted five years and killed nearly 400,000 civilians before the warring leaders Salva Kiir and Riek Machar agreed to lay down their arms.
Landmines and unexploded bombs still cover large areas of the world’s youngest country, posing yet another threat to a population already grappling with armed violence, natural disasters and hunger.
Globally, “every year, large numbers of civilians are killed and injured by `explosive remnants of war’ - unexploded shells, grenades, bombs, left behind after a conflict,” according to the International Committee of the Red Cross.
In June last year, the United Nations Office for Refugees said that experts from the United Nations Mine Action Service had destroyed more than one million explosive devices in South Sudan, including “40,121 mines, 76,879 cluster bombs and 974,968 other unexploded devices”.