Nearly half of the war-torn country is facing “catastrophic” food shortages, aid group warns.

Tens of thousands of people in South Sudan are on the brink of starvation with many living in swamps and surviving on water lilies and goat bones.

A hunger crisis affecting an estimated 4.8 million people could turn catastrophic unless humanitarian relief is urgently stepped up, Mercy Corps country director Deepmala Mahla warned.

“The situation is dire,” she said.

Mahla said the worst of the hunger is in the south of Unity State, where people have moved deep into swamp areas.

“People have been surviving for weeks, maybe months, just eating water lilies. People are also cooking goat skin and bones because there is nothing else,” she said, adding about 40,000 people are at risk of dying unless swift action is taken.

S Sudan: Aid workers caught in the crossfire

“It doesn’t take much time for a crisis to become a catastrophe. It’s a race against time.”

In the capital Juba, vegetable traders are now cutting tomatoes in half to sell because some customers can no longer afford to buy a whole one, Mahla said.

The crisis has been fuelled by nearly three years of war that has killed thousands, uprooted more than two million people, and disrupted markets. Inflation is at 661 percent – the highest rate in the world, Mahla said.

The fighting pits supporters loyal to President Salva Kiir against allies of his former deputy, Riek Machar. The pair signed a shaky peace deal a year ago but violence continues.

Mahla said the difficulties of delivering aid in a country the size of France with only 200km of paved road were compounded by increasing assaults on aid workers.

South Sudan had more attacks on aid workers than any other country last year, including shootings, rapes and mass lootings. At least 57 aid workers have been killed since the end of 2013 and many more are missing.

Across South Sudan many people have been uprooted multiple times meaning they cannot farm their land. Around South Sudan UN peacekeepers are protecting nearly 200,000 people at six compounds.

One third of children are out of school with girls being pulled out first to be married off in exchange for cows.

The United Nations estimates that half of the 12 million people in South Sudan, which gained independence from Sudan in 2011, are going hungry because of the conflict, poor rains, and a battered economy.

A version of this story first appeared on the Thomson Reuters Foundation news site