A dozen people, including Indian peacekeepers, have been killed in an attack on a UN convoy in Jongali state, east of South Sudan.

The country’s military spokesman Colonel Philip Aguer confirmed the death of five Indian peacekeepers and five UN civilian workers on Tuesday. However, a UN source said up to eight civilians were killed.

The head of the UN mission in South Sudan condemned the killings, saying the attack was launched by unknown assailants.

South Sudan’s military, however, blames the ambush on a group of fighters that it believes are supported by neighboring Sudan. Leaders in Sudan deny the accusation.

In July 2011, South Sudan voted to break away from Sudan following a two-decade civil war that killed thousands of people in Africa’s biggest country. But the new oil-rich nation, which is one of the least developed countries in the world, has had to confront ethnic tensions and rebellions of its own.