Shundure Tekamo faces a tough choice -- stay with her severely malnourished son in hospital, or return home in the desperate search for food for her five other children.

"I cannot think of anything, because I want only to save my child," she said, standing by the bedside of her baby son Berhanu in an emergency feeding centre.

"But I am worried because I left my other children," she added sadly.

This is the second time Berhanu has been in hospital for malnutrition since December, as his frail body struggles from a lack of food.

Some 4.5 million people in Ethiopia need assistance from the worst drought to hit the region in decades, according to the UN, with 12 million across the Horn of Africa affected.

Repeated years of erratic rains in Ethiopia's densely populated Southern Nations region have damaged or delayed crops, leaving thousands hungry.

At first glance the land around Shebedino, a small town some 225 kilometres (140 miles) south of the capital Addis Ababa, might not appear to be in crisis.

But the region faces a "green drought" -- while the landscape appears lush, crop harvests are delayed because of poor or delayed rains.

Over 250,000 people are in need of emergency food assistance in the southern region, according to government figures, although foreign aid officials estimate up to three times as many people could be struggling.

Aid workers say the crisis is the worst in years.

"The major causes of this food insecurity are recurrent drought, population pressure and degradation of land," said Getachew Lemma, the region's food security coordinator.

Conditions are expected to worsen in the coming months, the UN has warned.

"The malnutrition rate is increasing," said government food security expert Daniel Legisso, noting a five percent jump in malnutrition among children and lactating mothers since May.

"The current condition is very strained compared to previous years," he added.

For farmer Melcamu Tilahun, poor rains meant his maize crop died, and three of his four children are malnourished.

"This year I cant even feed my family for three weeks -- and its getting worse," he said.

In the past enough food was grown to get by for Melcamu's family, but now he wants to leave farming and become a small trader.

"If I can get credit and change my job, I can feed my family," he said.

The government has embarked on education campaigns to teach mothers to recognize signs of malnutrition, but there is also pressure to find long-term solutions to the crisis.

The UN World Food Programme runs a "safety net programme", a five-year scheme that provides food and cash in exchange for labour.

But there is a need for more irrigation schemes and greater access to fertilizer to support struggling farmers, said WFP program officer Yohannes Desta.

"For the long-term, there has to be diverse solutions," he said.

But for those struggling to survive like Shundure and her son, emergency relief remains the basic priority.

"Theres no food in my house to feed my children. I dont even have milk," she said.