The United Nations said Tuesday it needs further safety guarantees from armed groups in Somalia if it is to help hundreds of thousands of people in need of emergency aid because of drought and conflict in the East African country.

Aid groups have struggled to reach many of those affected because armed groups banished them from large parts of southern Somalia starting in 2009.

With thousands of people now on the brink of starvation, Somalia's most dangerous militant group, al-Shabab, has promised aid groups limited access to areas under their control.

But the UN refugee agency, which has distributed aid to 90,000 people in the capital Mogadishu and in southwest Somalia in recent days, said this wasn't enough.

"The situation we have for humanitarian workers inside Somalia at the moment is not what we want it to be," UNHCR spokesman Adrian Edwards told reporters in Geneva.

"We do have a very minimal presence, and we have regular visits into the country, but we need significantly better access than we have at the moment to address an emergency of this scale."

Worst drought in 60 years

The UN says over 11 million people in the region known as the Horn of Africa need emergency assistance after what is considered the worst drought in 60 years.

Many have left their homes seeking help in large refugee camps in Kenya and Ethiopia, making it easier for aid groups to reach them but raising the prospect of disease epidemics from large population movements and poor sanitation.

The UN has not yet declared the current food crisis a famine, but Brian Stewart, a distinguished senior fellow at the Munk School for Global Affairs at the University of Toronto, told CBC News that the UN is expected to declare a famine in some areas of Somalia within 48 hours.

In parts of the Horn of Africa, food insecurity has already reached emergency levels — one level below famine. "Famine/catastrophe" is the worst-case scenario on a five-level scale used to gauge food security.

The scale uses several indicators to declare a famine, including acute malnutrition in more than 30 per cent of children, at least two deaths per 10,000 people every day and access to less than four litres of water a day. Large-scale displacement of people, civil strife and pandemic illness are also taken into consideration.

The last time a major famine was declared in the Horn of Africa was 1984-85, when a catastrophic drought in Ethiopia left more than one million people dead.

The formal conditions for declaring a famine are present across at least parts of the border region between Somalia, Ethiopia and Kenya.

"If you look at what's going on the ground, you look at the pictures, you listen to what everybody is saying, it's a very serious situation, whether you use that word or not," Emilia Casella, a spokeswoman for the World Food Program, told The Associated Press.

WFP has offices in four regions of Somalia from where it is trying to feed 1.5 million people, she said.

But the agency estimates that as many as one million people are in areas it can't currently access.

"One we have the assurances of security and the ability to have full access to deliver and distribute and monitor, then we will be prepared to go back in," said Casella.

To date in 2011, the government of Canada has provided $22.35 million for humanitarian assistance in East Africa, including more than $11 million for aid to Somalia and Ethiopia, according to the Canadian International Development Agency. With files from CBC