JUBA: At least 169 people have been killed and buried in a mass grave in northern South Sudan, two local officials said on Monday, as the country sees a dramatic increase in violence.

South Sudan, the world’s youngest country, has been beset by civil war, poverty and massive corruption since it was formed in 2011.

The UN warns of a return to “all-out civil war” as a power-sharing deal between President Salva Kiir and his long-time rival, Riek Machar, has unraveled over the past year.

The desperately poor east African country also faces chronic ethnic violence and violent cattle-raiding.

• South Sudan, the world’s youngest country, has been beset by civil war, poverty and massive corruption since it was formed in 2011.