Aid workers estimate that about 400,000 people have fled the capital, Mogadishu, since February to seek shelter in other regions of the country. As a result, many host communities have more than doubled in size.
"The conflict and displacement have severely disrupted economic activities, which is particularly [affecting] poor urban households that rely on petty trade and casual labour as their main sources of income," the Famine Early Warning Systems Network (FEWS Net) said in a joint statement with the United Nations Food and Agriculture Organization/Food Security Analysis Unit.
"In host communities outside Mogadishu, the inflows of IDPs [internally displaced persons] have increased competition for already overburdened social services, markets, housing and employment opportunities," it added.
According to FEWS Net, 38 percent of Mogadishu's displaced population has moved to Shabelle region, 38 percent to Mudug and Galgadud and the rest to Hiran, Bay, Gedo, Juba, Bakool and the northern regions. Another 3,500 people are in Doble town, near the closed Kenyan border.
Retail prices soar
In Mogadishu, it is estimated that 30 to 40 percent of the population, especially poor households and former IDPs, are displaced within the city.
"The increased competition is especially limiting food access in the south, where rural populations are still recovering from conflict and recurrent shocks of drought and floods," the statement said. Retail prices increased dramatically as trade flows were restricted, while demand increased substantially in host-community markets around Mogadishu.
In the Shabelle and Bay regions, imported commodity prices rose between 20 and 70 percent between March and April and locally produced maize prices have increased between 50 and 120 percent since January.
"The loss of income and sharp price increases have caused food access to deteriorate substantially for poor households, IDPs and host communities," the statement added. "These households are at the edge of their coping capacity."
Somalia, which has been without an effective government for one-and-a-half decades, has witnessed intense clashes between Ethiopian-backed government troops and insurgents since February. This has curtailed efforts to deliver aid to those affected.
On Sunday, the UN World Food Programme (WFP) appealed for high-level international action to stamp out piracy in waters off Somalia, warning that the flow of relief supplies to the country was under severe threat.
The appeal followed the killing of a Somali guard who helped defend an attack on a ship that had just delivered food to the port of Merka. "We urge key nations to do their utmost to address this plague of piracy, which is now threatening our ability to feed one million Somalis," said WFP Executive Director Josette Sheeran from the agency's Rome headquarters.
WFP has, despite major operational and security challenges, continued to deliver food to thousands of vulnerable Somalis, and on Friday began a new round of distributions targeting the 122,500 people who fled fighting in Mogadishu.