Secretary-General Ban Ki-moon has said that "uncertainties" remain about whether a UN peacekeeping force is the right tool to support the new Somalian government's efforts to establish itself and promote national reconciliation.
Mr Ban said in his quarterly report to the UN Security Council that he would provide further advice and recommendations on the deployment of a peacekeeping operation by April 15 and will continue to update and revise contingency plans for a UN force.
The Security Council adopted a resolution in December expressing its intention to establish a UN peacekeeping mission in Somalia, but putting off a decision for several months in order to assess the volatile situation in the Horn of Africa nation.
The council said the decision should be made by June 1.
Somalia has been beset by 18 years of anarchy, violence and an Islamic insurgency that has killed thousands of civilians and sent hundreds of thousands fleeing for their lives.
The African Union, which has about 3,500 troops protecting vital installations in the capital, Mogadishu, has been pressing for months for the UN to take over peacekeeping - and so was the former US administration of President George Bush, but President Barack Obama is reported to be less enthusiastic.
Mr Ban said he was encouraged by the expansion of Somalia's parliament and its election of Sheik Ahmed Sheik Sharif as the country's leader after the former president resigned, and by "the determination of the people and leaders of Somalia to carry on with the reconciliation process".
At the same time, he said "the security situation in Somalia remained volatile" with widespread fighting in Mogadishu following the withdrawal of Ethiopian forces in January, and insurgent fighters gaining control over additional towns and territory although they are increasingly facing armed resistance from clans and other local militias.
More than three million Somalis need humanitarian assistance, and in many parts of the country the rates of acute malnutrition remain above emergency thresholds, he said, but "the instability generated by the fighting, ongoing abductions and a general atmosphere of fear continue to impede the effective delivery of humanitarian assistance to the many people who need it".
In 2008, Mr Ban said 34 aid workers were killed in Somalia, 26 were abducted, and 13 were still in captivity at the end of January.
"I therefore pay tribute to all the organisations and personnel involved in the delivery of humanitarian assistance ... (who) continue to discharge their responsibilities in an extremely dangerous and stressful environment," he said.