South Sudan's main rebel group accuses government of violating ceasefire

South Sudan's main rebel force SPLM-IO has accused the government's forces of attacking their defensive positions just a day after both sides signed a peace deal.

President Salva Kiir signed a peace agreement with rebel factions in the Ethiopian capital on Wednesday to end a civil war that has killed at least 50,000 people, displaced some three million and held up the country's progress since it gained independence seven years ago.

"The regime's forces heavily stormed our position at Mundu in Lainya county," said Lam Paul Gabriel, the rebels' deputy military spokesman, in a statement seen by Reuters on Saturday.

He said the attack happened in the early hours of Friday and that eight government troops were killed in the ensuing battle. Another attack took place in Mangalatore, near the site of the first attack, where four government soldiers were killed, the statement said.

Both Mundu and Mangalatore are in Yei River State, close to the border with Uganda.

There was no immediate comment from the government or international mediators.

The stability of South Sudan is important for Sudan and other neighboring countries, who fear a new flare-up of the conflict could flood them with refugees.

The civil war started in 2013, fuelled by personal and ethnic rivalries. The conflict has killed at least 50,000 people, many of them civilians, according to the United Nations.

An estimated quarter of South Sudan's population of 12 million has been displaced and its economy, which heavily relies on crude oil production, ruined.