Clashes over access to resources and cattle rustling are frequent in the poverty-stricken east African nation, which also faces extreme droughts and floods.

Conflicts among cattle herders have become rampant in Tonj East, located in Warrap State in northwestern South Sudan, causing "hundreds of deaths, the destruction of homes and widespread displacement," according to the United Nations Mission in South Sudan (UNMISS).

"In March, more than 200 people are estimated to have died during the intercommunal conflict," UNMISS said in a statement.

"Urgent intervention is needed from the national government to prevent the conflict from escalating to catastrophic levels and to bring communities together to peacefully resolve grievances," said Guang Cong, the UNMISS deputy special representative.

In February, a local official denounced a "cold-blooded massacre" in the southern Eastern Equatoria state where 41 people including women and children were killed, while 65 were wounded and many others went missing, the statement said.

Such localised conflicts have further deepened the crisis in South Sudan, which has been beset by political instability and ethnic violence since it gained independence from Sudan in 2011.

The nation has also faced months of localised clashes between forces loyal to President Salva Kiir and his long-time rival, First Vice President Riek Machar.