Ethiopia has called for humanitarian corridors in Somalia to be protected by peacekeepers, so that aid can reach famine-hit areas held by rebels.
Prime Minister Meles Zenawi suggested the move at a regional summit in Kenya on the East Africa drought and famine.
But UN humanitarian co-ordinator for Somalia Mark Bowden said aid deliveries were increasing and efforts to provide armed protection could jeopardise them.
The UN says 750,000 people could die in Somalia's famine within four months.
Flow of refugees
Mr Meles told Horn of Africa leaders "huge areas" of Somalia remained unreachable.
"Many districts are in control of al-Shabab terrorists. We need to urgently support the TFG [transitional federal government], AMISOM [African Union Mission in Somalia] and other forces to create corridors of humanitarian assistance in the liberated areas and beyond," he said.
Mr Meles said more food aid needed to be delivered to the affected areas to minimise the flow of refugees from Somalia. Ethiopia shares a border with Somalia.
East Africa correspondent Will Ross says Mr Meles's suggestion is controversial. Observers say using peacekeepers to guard aid routes would undermine negotiations on delivery with the Islamist al-Shabab group.
In July, al-Shabab lifted a ban on aid organisations operating inside Somalia, but reimposed it after the United Nations declared a famine in parts of the country.
Our correspondent says restrictions imposed by the group have hampered the aid effort and most people agree that food aid is not reaching enough people in Somalia.
Regional leaders meeting in Kenya on Friday agreed a solution to the political crisis and conflict in Somalia was needed.
In a document - to be known as the Nairobi Action Plan - they pledged to ensure future droughts do not cause such suffering and agreed to invest in arid areas to help livestock-keeping communities become more resilient.