South Sudan has declared a humanitarian disaster in the state of Jonglei, the site of repeated tribal clashes that have killed hundreds of people.

A government spokesman says South Sudan's council of ministers declared the disaster at a special meeting Wednesday, and asked international relief agencies to quickly deliver aid to the state.

A group of 6,000 fighters from Lou Nuer tribe attacked the towns of Lukangol and Pibor last week, setting fire to huts and prompting tens of thousands of civilians to flee. Pibor is home to the Murle tribe, which was blamed for attacks on Lou-Nuer areas in August.

The government says its forces have asserted control of Pibor and says it will try to arrange reconciliation talks between the tribes.

The government is also directing the tribes to return kidnapped women and children to their home communities.

The United Nations says communal violence in Jonglei state killed more than 1,100 people during 2011 and displaced more than 60,000 others.

South Sudan has been plagued with tribal and militia violence since become independent from Sudan in July.