The famine in East Africa has not peaked and hundreds of thousands face starvation and death, the United Nations has warned.
Video:Plan International co-ordinator on East Africa's crisis
Dr Unni Krishnan describes the crisis unfolding in East Africa.
Video:Plan International distributes aid in Ethiopia
Plan International distributes cooking oil, maize flour and beans in the district of Wondogenet, Southern Ethiopia.
The crisis is expected to spread to all regions of south Somalia in the next four to six weeks unless further aid can be delivered.
The UN has received less than half of the $2.4 billion it requested from donor countries and its deputy emergency relief coordinator appealed to the international community for $1.3 billion needed urgently to save lives.
"Every day counts," Catherine Bragg told the UN Security Council. "We believe tens of thousands have already died. Hundreds of thousands face imminent starvation and death. We can act to prevent further loss of life and ensure the survival of those who are on the brink of death."
The UN's food agency said yesterday it has been able to reach more parts of Somalia in the past month but Mogadishu remains dangerous, even though Islamist rebels have left the capital.
About 3.6 million people in Somalia are at risk of starvation. The worst-hit Somalis live in areas controlled by Al Shabab militants and many have risked their lives to travel to Mogadishu and elsewhere in search of food aid.
The rebels withdrew from the capital at the weekend, but they said it was a tactical move and there have still been outbreaks of fighting.
The militants, who oppose western intervention, imposed a ban on aid agencies. They say aid creates dependency. They lifted the ban last month when the food crisis hit critical levels, only to apparently renege on it.
"We have, over the past month, gained additional access to areas which previously we were not able to operate in," Stanlake Samkange, the World Food Programme's regional director for east and central Africa, said yesterday.
"What we've seen over the past few weeks is that additional pockets have opened up where we are able to provide assistance within Somali areas that previously were not accessible to us. And I would say the trend is much more in that direction."
Mr Samkange declined to say which areas the agency now had access to because he feared they could become targets.
The WFP had been saying aid agencies have not been able to reach more than two million Somalis in the worst-hit areas, which are mostly in southern Somalia, because Al Shabab had blocked access to most aid organisations. WFP now provides assistance to more than 1.5 million people in Somalia's famine zone.
* With reporting by Reuters and the Associated Press