Though this country produces sufficient food for its population, skyrocketing prices prevent the poor - most of them urban households - from getting adequate nutrition .

The hungriest people are in Cape Town (80%) and Msunduzi, in KwaZulu-Natal (87%).

A five-year study by the University of Cape Town's African Food Security Unit Network has exposed a food crisis that constitutes a "death sentence" for many and which the government has labelled as "serious".

It found that, in Johannesburg, 43% of the poor faced starvation and malnutrition. Researchers believe the figure could be higher.

According to the UN Food and Agricultural Organisation, 870 million people worldwide are chronically undernourished, 234million of them living in sub-Saharan Africa.

The plight of the hungry was highlighted in 2011 when four children, aged between two and nine, died in a farmer's field as they began an 18km walk in search of their mother and food in Verdwaal, North West. It was later discovered that they had not eaten for more than a week.

The Department of Agriculture, Forestry and Fisheries last week revealed that 12million South Africans are "food insecure".

Food security refers to the ability to access adequate nutrition - food that is affordable, hygienic and culturally accepted.

Food Bank SA spokesman Keri Uys said yesterday: "South Africa is in dire straights. The entire country is affected. It is not just rural areas.

"Every day millions of people go to be bed hungry. There are children whose daily food is half a white-bread sandwich. How can you bring up a nation on this?"

"The implication is a death sentence."

The network's Dr Jane Battersby-Lennard said the University of Cape Town study focused on poor areas in 11 cities in the Southern African Development Community, including Cape Town, Johannesburg and Msunduzi.

The survey covered 1060 households in each city.

Battersby-Lennard said the number of South Africans subject to food insecurity could be far higher than the survey suggested.

"The figures from the surveyed cities show 77% of all households were either moderately or severely food insecure.

"When it comes to South Africa, two of the surveyed cities were higher than this, which is dire. The challenge of food security in our cities is greater than imagined."

She said the problem was access to adequate nutrition, not the availability of food.

"This is because of poverty. People are simply too poor to buy food. On top of this, poor areas have seven times fewer supermarkets than rich areas, making it a struggle to access nutritional food.

"This forces households, especially those that run out of money before the end of the month, to borrow and buy food on credit.

"If supermarkets do move to these [poor] areas it often forces informal food traders out of business, making people more food insecure."

She said the government had identified food security as a "critical challenge".

"Though a higher proportion of rural households face food insecurity, when you look at the different scales of food insecurity - which range from mild to moderate and severe - more urban households fall within the severe food insecurity category.

"Severe food insecurity means households are forced to cut back on meal sizes and numbers, with people going hungry for days. Our urban population is facing severe malnourishment."

The study found two distinct heightened hunger periods - January, and during winter. On average, the poorest households surveyed spent 53% of their income on food.

Department of Agriculture, Forestry and Fisheries spokesman Palesa Mokomele said that if 12million people were subject to food insecurity it implied that about 4million households faced starvation.

"These are families often relying on only one kind of food, such as maize, often not in regular supply.

"The government is concerned ... it is a crisis."

Joe Kgobokoe, the department's chief director for food security and agrarian reform, said a "host of programmes" addressed the crisis.

"[The department] promotes food gardens at homes and schools, and assists rural smallhold ers to produce food."