The victims, many of whom fled their homes to escape militia violence, suffer from severely restricted access to food and income, the Food Security Analysis Unit (FSAU), part of the United Nations Food and Agriculture Programme, said.
Its report released on Friday blamed the situation on poor crop and livestock production, limited markets for their labour and produce, loss of cereal and livestock assets, and deteriorating terms of trade as a result of rising cereal prices and falling livestock prices.
In the North, Central and Southern Regions of Somalia an estimated 1.7 million people are facing acute food and livelihood crisis or humanitarian emergency at least until June, the FSAU said after a visit to the country last month.
An estimated 380,000 people who fled their homes to escape the violence in anarchic Somalia also need help, according to the group which works with UN, US and European aid groups.
Somalia has had no effective central government since opposition leaders ousted its ruler Mohamed Siad Barre in 1991.
They then turned on each other, transforming the nation of an estimated 8.2 million into a patchwork of battling fiefdoms ruled by heavily armed militias.
Even before this crisis, acute malnutrition rates in many of the affected areas were already among the worst in the region, according to the group.
The victims suffer from restricted
access to food and income
Somalis hit by the crisis need food and water aid, cash assistance, health and nutrition assistance, the protection of vulnerable groups and assistance to protect livestock.
The UN food aid agency has said that preliminary assessments show that an estimated 11.5 million people in East Africa will require food assistance in the coming months.
The regional scope of the drought prevents Somalis from migrating to neighbouring countries to seek food, water and pastures.
Meanwhile, piracy off Somalia's coast has forced the UN food aid agency to stop using cargo ships to deliver food aid, which is required by some Somalis year-round.
Trucking the food through the lawless country has created numerous other problems adding to the difficulties of getting aid delivered to those who need it.