JUBA - An outbreak of hepatitis E has killed 88 people in South Sudan after a surge in the virus hit refugee camps near the Sudanese border, an aid agency said on Saturday.

More than 175,000 people have sought refuge in the new country of South Sudan after fleeing fighting in Sudan's restive border states of South Kordofan and Blue Nile, according to the United Nations.

Medical charity Medecins Sans Frontieres (MSF) said it had treated almost 4,000 patients since the outbreak was identified in camps in the northeast of South Sudan in July 2012.

"We suspect this outbreak is far from over, and many more people will die," said MSF said in a statement.

"We have been doing everything we can to care for people with hepatitis E, but there is no treatment for the disease."

Fighting between Sudan's army and rebels flared up in South Kordofan and Blue Nile around South Sudan's secession from Sudan in July 2011, six years after a peace accord that ended decades of civil war between north and south.

Tensions remain high between the rival Sudans and they have failed to implement a raft of agreements on border security and economic issues left over from their messy divorce.

More than 112,000 Sudanese refugees live in camps affected by the hepatitis outbreak which are flooded in the rainy season and a parched wasteland in the dry season, MSF said.

Hepatitis E causes liver infections and is spread by drinking water contaminated with faeces.