Ongoing clashes have forced over a million people in South Sudan from their homes during more than three months of turmoil, with conditions continuing to worsen, the United Nations warned Friday.

"In the 100 days since the start of the conflict in South Sudan, over one million people have fled their homes," the United Nations Office for the Coordination of Humanitarian Affairs (OCHA) said in a report late Friday.

Over 800,000 are displaced inside South Sudan, while almost 255,000 have fled as refugees to neighboring countries of Ethiopia, Kenya, Uganda and Sudan, the U.N. says.

One million people have received humanitarian assistance, a number OCHA says will rise to 3 million by June. The full U.N. report is available here [PDF].

But overall, 4.9 million people need humanitarian assistance in a country of around 11.5 million. Almost half of South Sudan is under the age of 14.

Violence erupted in South Sudan on December 15 between forces loyal to President Salva Kiir and fighters loosely allied to former vice president Riek Machar.

A ceasefire between government and rebels inked in January is in tatters with fighting ongoing.

"Fighting between government and opposition forces has continued, especially in Jonglei, Unity and Upper Nile state, where towns and rural areas have been ravaged by the violence," the OCHA report added.

The conflict has caused a "serious deterioration in the food security situation" with some 3.7 million people at high risk, it read.

Peace talks in the Ethiopian capital Adis Ababa have made little if any progress, with the two sides spending time squabbling in luxury hotels over who can attend negotiations.

Tens of thousands of civilians are sheltering inside U.N. peacekeeper bases fearing revenge attacks, crammed into tiny areas in increasingly squalid conditions due to heavy rains.

The U.N. estimates five million people are in need of aid, with vast swathes of the countryside increasingly difficult to reach by road due to seasonal heavy rains.

Huge warehouses of food aid stored for the rainy season before fighting broke out have been looted.

The U.N. World Food Program has therefore begun delivering food and medical supplies by costly air drops. In places without an effective runway the food sacks are simply dropped out of the back of cargo jets.

Jonathan Veitch, UNICEF chief in South Sudan, warned Friday of "worrying signs of malnutrition and disease outbreaks" and that every effort had to made to "avert a humanitarian catastrophe."

Chris Nikoi, head of WFP in South Sudan, said he was "enormously concerned that things could get worse.”

Al Jazeera and AFP