Benjamin Lat, information minister in the West Lakes state, said violence between the Jack and Manoir ethnic groups erupted on November 27 and lasted for several days.
He added: "The killing was to take revenge, after the killing of members of the ethnicity of Jack, one of the ethnicity of Manoir and the government intervened."
The United Nations Mission in South Sudan (UNMISS) said in a statement that it had sent Nepalese soldiers, as part of the peacekeeping force, to the region after reports from local authorities that up to 79 people were killed and 101 injured in a series of clashes in the western lakes.
Oil-producing South Sudan, which became independent from Sudan in 2011, plunged into civil war in 2013 after President Salva Kiir sacked former rebel leader Riek Machar from the post of vice president.
After five years of conflict, Kiir and Machar signed a peace deal in September 2018 but have yet to agree on a unity government.
On the seventh of November, the two leaders agreed to give themselves a 100-day deadline after the deadline, which expired on 12 November to form a unity government.
An estimated 400,000 people have been killed in the conflict, causing famine and the largest refugee crisis in Africa since the 1994 genocide in Rwanda.