A serious food crisis in the north of South Sudan is reaching critical levels, as a biting drought across much of east Africa serves up even more woes for the troubled country.

In Northern Bahr Al Gazal it is not the incessant cycles of violence wreaking havoc elsewhere in the country that concerns locals most, but the lack of rain and a deep economic crisis.

At a clinic run by Doctors Without Borders (MSF) in the town of Aweil, Lucia Adeng holds her three-year-old son Wek Wol Wek, his breathing shallow and rapid and his skin paper thin around his emaciated arms.

"It's not always a total lack of food, but there is definitely a shortage. Sometimes we have food at home, and sometimes we don't," she says.

Several children like him lie silent in their mothers' arms, their eyes downcast, as they are poked and prodded by doctors. The clinic is currently recording about 60 cases of malnutrition a week, according to MSF.

Out in the fields, farmer Tong Deng looks miserably at his damaged sorghum crops and tiny yield from the lack of rains. For others, when the rains came, it was too much, with sudden massive downpours in August causing flooding which also ruined their crops.

"Our harvest has been low because during the planting period the hunger situation was very severe for us and we were not able to cultivate much land. We were hungry," Deng.

"At the same time, what we cultivated suffered a dry spell which didn't allow a good germination, and later the few crops were affected by the sorghum midge."

At the local market, several stalls are closed and offerings are meagre.

- 40 percent going hungry -

The World Food Programme (WFP) warns that as many as 4.8 million people - about 40 percent of the country's population -- were going hungry and that the situation would only get worse.

The Famine Early Warning System Network (Fews Net) last month said some households were already at the "catastrophic" famine level 5, meaning "starvation, death, and destitution are evident."

Others were going several days without a meal, placing them in "emergency" level.

With roads from Sudan blocked to trade goods, and those to Uganda fraught with danger due to clashes between government and rebel forces, the inflation in prices of certain cereals is as much as 1,000 percent in some states, according to the National Statistics Bureau.

A depreciation of the South Sudanese pound has also hit hard.

The Food and Agricultural Organisation (FAO) says that more than 70,000 people from the region have migrated to Sudan to escape the harsh conditions.

In other parts of the country, it is fighting between opposition forces loyal to former vice president Riek Machar and his rival President Salva Kiir that has displaced hundreds of thousands, severely impacting the cycle of planting and harvesting.

South Sudan gained independence from Sudan in July 2011. According to the reports of the Integrated Food Security Phase Classification (IPC), food insecurity has increased 500 percent since 2012.

The country descended into war over the political rivalry between Machar and Kiir in 2013, and a fragile peace deal signed in 2015 is in tatters, with fighting erupting again in July and a surge of violence in recent weeks.

The Pacific warming El Nino caused one of the worst droughts in decades in 2015 across eastern and southern Africa and the 2016 rainy season has been slow to start, meaning the crisis could drag on for several months.