Hundreds of Somali women, huddled together with their children, queue for hours for their first cooked meal in days, having walked long distances to flee drought, famine and conflict.

"On the road here I was so hungry and thirsty," said Batulo Malim Mohamed, waiting patiently for a meal of fortified maize porridge in the shade of a hut at a new feeding centre erected in the southwestern border town of Doolow.

"When I first arrived I had nothing, so I had to beg people for some food," she added, cradling her malnourished son Ali in her arms.

Many trekked for days from all over southern Somalia to reach Doolow, a war-damaged town in the Gedo region, where tens of thousands of displaced people have passed through.

Most travelled on foot, some by donkey cart -- only a lucky few could pay for a lift.

Doolow is the last stopping point before people cross into refugee camps in Ethiopia, with a constant flow of over 2,000 people here at any given time, according to the UN refugee agency.

Responding to the rising demand, the UN children's agency UNICEF on Thursday opened the new feeding centre at Doolow for those arriving exhausted, some having walked for more than a week.

Servings of hot porridge with sugar, cooking oil and special nutrients is handed out in plastic cups to some 900 people, many of whom waited all morning on the centre's opening day -- double the number the UN had expected.

Panic breaks out when a rumour spreads that the food is running out and the desperate crowd pushes past the armed soldiers into the distribution area.

"It took me nine days to get here from Wajid" about 150 kilometres (93 miles) east, Habiba Isack tells AFP, her six-month old son strapped to her back.

"On the way I was very hungry, we had no money to buy food. My husband sent me here alone, so I had to make the journey carrying my children. I thought I'd die from hunger."

The simple meal is enough to persuade many to stay rather than continue the trek onwards to Ethiopia.

"If I can get help here, then I will stay," said 23-year-old Fardowso Diriye. She made the eight-day journey from Baidoa (about 230 kilometres away) carrying her own child and the son of her sister-in-law who had died from starvation.

"I now have to look after him," Diriye said.

The United Nations on Wednesday declared three more southern Somali areas, including the capital Mogadishu, as famine-struck, and warned the crisis could still spread further.

The crisis has stretched aid workers to their limits.

"We found more people than we anticipated," said Erin McClowskey, a nutrition specialist with UNICEF, overseeing the first day of feeding in Doolow.

"I've just looked at the registration books now, and it is about double what I thought."

The aid agency hopes by providing food the displaced people will not have to cross into Ethiopia, where tens of thousands of drought refugees have arrived since the beginning of the year.

"People don't want to leave Somalia, it is their home. They don't want to go to Ethiopia or Kenya and be in camps," McClowskey added.

"We're hoping this provides some way for them to stay in the country -- at least for a short time -- until they decide what to do next."

But apart from food, there are few facilities.

"I don't have a place to sleep," says Fatima Hared. "The moment the sun goes down we just sleep out in the open, wherever we are."

A camp is being set up on the outskirts of the town to provide some shelter, with a basic health centre.

Despite the enormous demand, shops in Doolow town are still stocked with food.

However, those most in need cannot afford to buy any -- costs of staple grains have more than doubled since last year.

The UN has warned that drought-hit Somalia is "the most severe humanitarian crisis in the world today and Africa's worst food security crisis since Somalia's 1991-92 famine."

Much of southern Somalia -- including the majority of regions declared to be in famine by the UN -- is controlled by Islamist Shebab rebels, who continue to ban several key aid agencies from operating.

Doolow is controlled by forces supporting the embattled Western-backed government.