Displaced people living in some camps in South Sudan say they feel insecure because some fellow refugees are armed.
The guns are sometimes used in the camps during minor conflicts leading to the deaths of some refugees.
The humanitarian organisations last Friday issued a report warning that the armed refugees endangered the lives of displaced people and aid workers.
According to the report, aid agencies are implementing a number of measures to rid the camps of dangerous weapons.
Registration personnel have been empowered to detect armed elements," the groups said.
"They have started getting some of the armed refugees," said Julius Ogwa, a volunteer at one of the camps.
"The guns are removed from them and handed to the police.'"
Refugees said the dangerous weapons were often used to settle petty fights at the camps.
"There are some of us who have guns," said Chris Oneg, a refugee in Maban refugee camp.
"We are scared of such people because when we quarrel with them they threaten to shoot us."
Humanitarian organisations have also confirmed the presence of armed refugees at the camps.
Camps where humanitarian groups said there were many armed refugees are located in the Maban County in Upper Nile State.
The Maban County camp has more than 100 000 refugees.
Meanwhile, the humanitarian organisations said they expect food shortages to worsen in South Sudan due to recent floods.
Aid agencies expect the number of people who need food aid next year to top 2.3 million.
The floods destroyed crops and left thousands of domestic animals dead.