Parts of Africa and the Middle East face their worst drought in almost 70 years with a significant risk of starvation leading to “mass deaths”, the United Nations refugee agency has warned.

Four countries – Nigeria, Somalia, South Sudan and Yemen – stand on the brink of a new humanitarian crisis brought about by drought and famine.

Aid agencies have told The Independent that the bleak situation is likely to worsen significantly in the coming months as the so-called hunger gap takes hold.

The numbers, released by the UNHCR, are staggering: 20 million people live in areas where harvests have failed and malnutrition rates are increasing, particularly among young children. One million people are now on the brink of famine.

​UNHCR has raised its projections for the number of refugees displaced from their homes in the region, including in South Sudan and Somalia, where hundreds of thousands have been forced to flee their homes to find food.

The UN agency blamed a combination of war, political instability and environmental factors including climate change and said it was “scaling up” its efforts in the region.

“The world’s most vulnerable in the Horn of Africa, Yemen and Nigeria are running out of time,” UNHCR spokesperson Babar Baloch told The Independent. “The risk of death from starvation is real.

“Time is of the essence here. If there ever was a more needed time for solidarity from the international community and individuals who can donate, it is now.”

He said the agency was preparing for a crisis at least as bad as in 2011, when over a quarter million people lost their lives in a drought described at the time as the worst in 60 years.

Somalia, a Horn of Africa country of 12 million people, is facing its third famine in 25 years of civil war and anarchy (Getty)

That could soon be eclipsed by this year's drought and famine, which is compounded by a funding shortfall that has meant an avoidable humanitarian crisis “is fast becoming an inevitability”, UNHCR said.

Overall the UN has appealed for $4.4bn (£3.5bn) for the four countries but has received less than $984m (£790m) – or 21 per cent – to date.

In Yemen, home to the world’s largest humanitarian crisis with almost 19 million people in need of aid, the situation is “nothing less than catastrophic”, according to Shabia Mantoo, the agency’s spokesperson for the country.

She told The Independent: “Millions are going hungry, displaced, in danger and languishing in abysmal conditions.

“Those affected and displaced by conflict are struggling to meet primary needs – food, water and shelter.

“People are dying, either directly as a result of conflict of because of preventable causes, others are living on the streets, more and more children are becoming malnourished and those most vulnerable, women and children in particular, are resorting to desperate measures to try and sustain themselves and their families at the risk of exploitation and abuse.”

Disasters Emergency Committee in Africa famine appeal

In South Sudan, the world's youngest nation, close to one in five of the population has been displaced by the drought.

Juliette Stevenson, a UNHCR representative based in the capital of Juba, told The Independent: “The people in South Sudan continue to suffer immensely.

“There are over 1.9 million people displaced inside the country due to conflict, with many of them difficult to reach because of both the rampant insecurity and the huge logistical challenges working a country with vast distances and very few roads.”

Of particular concern to aid agencies are the summer months of June, July and August – known as the 'hunger gap' or lean season – when populations run out of food from the previous growing season but next year’s crops are not ready for harvest.

A spokesperson for Médecins Sans Frontières (MSF) said the agency’s medical teams were “scaling up” their efforts in Nigeria in preparation for an expected surge in hunger and malnutrition during the 'hunger gap'.

In the north-east of the country alone, food insecurity is projected to affect 5.2 million people over the three month period.

Surviving Somalia: Photographer Ed Ou visits a food project as famine strikes in the East African nation Show all 11 1 /11 Surviving Somalia: Photographer Ed Ou visits a food project as famine strikes in the East African nation Surviving Somalia: Photographer Ed Ou visits a food project as famine strikes in the East African nation Nadifo Yusuf, aged 25, with her five-month-old child at the New Shabelle Internally Displaced People (IDP) camp in Bosaso, Somalia. Says photographer Ed Ou: 'She fled on the back of a truck with her family after her husband was killed in the south of Somalia. She paid $30 for a truck ride, but was robbed by bandits in the night, which happens to a lot of people - so she'd had to beg for food along the way.' Ed Ou Surviving Somalia: Photographer Ed Ou visits a food project as famine strikes in the East African nation A mother collects food from Save the Children. 'People had to queue for two hours to get food and it was very hot. They get given a bottle of cooking oil, then maybe 15 or 20 packets of a very high-calorie peanut paste specifically designed for children - it's got 500 calories per pack. They also get high-nutrient flour which they then cook up into bread.' Ed Ou Surviving Somalia: Photographer Ed Ou visits a food project as famine strikes in the East African nation Severely malnourished 11-month-old, Naimia Isaq Abdi, at a Stabilisation Centre in Bosaso. She weighs in at 5.5kg. 'They had to weigh people to see if they qualified, if they were eligible, as well as tracking whether they were growing - they would weigh the children in these buckets and then measure their arms.' Ed Ou Surviving Somalia: Photographer Ed Ou visits a food project as famine strikes in the East African nation Habibo Ali Mursal, aged 30, lies with her malnourished one-year-old baby, Sharifo Malin Mohamed, who weighs 5kg. 'Stabilisation centres are for more extreme cases, for people who are so malnourished they can't eat properly. The nurses pass out water and food but there are some children who have to take food in through the nose, perhaps if they're not conscious.' Ed Ou Surviving Somalia: Photographer Ed Ou visits a food project as famine strikes in the East African nation 'The food was supplied by the World Food Programme. Everyone had an identification card which was filled in and basically tracked how big their child was. It's pretty orderly - maybe because it's women and children. They knew they were about to get their food, it wasn't a desperate grab.' Ed Ou Surviving Somalia: Photographer Ed Ou visits a food project as famine strikes in the East African nation 'There were 6,000 people just at the New Shabelle camp. On my last day, there was a food hand-out and it seemed like they gave almost all of it out - they got through 50 boxes of peanut paste. Looking at the scope of the food hand-outs, you realised demand outweighed supply.' Ed Ou Surviving Somalia: Photographer Ed Ou visits a food project as famine strikes in the East African nation A Somali woman stands over the only goat she has left in her pen inKarkaar, Somalia. 'She had over 60 goats, but they all died in the recent drought.' Ed Ou Surviving Somalia: Photographer Ed Ou visits a food project as famine strikes in the East African nation Yusuf carries water to her tent. 'Like any IDP camp they are in a pretty desperate situation. A lot of these camps have existed for some time but recently there's been a big influx. The toilet is an open field right by the water supply.' Ed Ou Surviving Somalia: Photographer Ed Ou visits a food project as famine strikes in the East African nation The New Shabelle camp. 'Most of the shacks are made out of sticks - sticks are constructed into domes and then laced with cardboard and fabric, as much as they can.' Ed Ou Surviving Somalia: Photographer Ed Ou visits a food project as famine strikes in the East African nation A new arrival builds a makeshift shelter. 'During the time we were there, we met new arrivals. There were maybe about 30 coming each day, but there are many different camps - there are 31 camps just around Bosaso - so it's hard to tell how many people are arriving.' Ed Ou Surviving Somalia: Photographer Ed Ou visits a food project as famine strikes in the East African nation Aniso Osman Hussein, aged 13, with her malnourished brother, Diini Osman Hussein, aged three and weighing 10.5kg, at the stabilisation centre. 'People are getting the amount of food they need - it's just there's a lot of people there now that need it. In order for everybody to get enough food, more needs to get there.' Ed Ou

Peter Lundberg, the UN deputy humanitarian coordinator for Nigeria, said the lean season also combined with Nigeria’s rainy season, making hard-to-reach communities even more inaccessible.

“In other circumstances we would pre-position food, but here that is a problem because of the conflict,” he told The Independent. “The Nigerian army is not happy to bring food and store it in remote areas.

“We may open up other routes from Cameroon, but we’re also looking at taking food in by air, but that will be the last resort as it is extremely expensive.

“As it stands right now they will not even have food for the lean season as the current funding promised only lasts until June.