The United Nations warned Thursday that Ethiopia's reported sending of troops into Somalia to fight Islamist rebels could worsen what is already the world's most severe humanitarian crisis.
"Local sources report that hundreds of Ethiopian troops entered Somalia on November 20 opening a new front against Al-Shebab," the UN Office for the Coordination of Humanitarian Affairs said in a report.
"The humanitarian community is deeply concerned about the consequences that this intervention could have on the already fragile humanitarian situation due to access to the population," the report warned.
"The intensification of the conflict in Somalia threatens to increase internal displacement," it added, the first time the United Nations has warned of the potentially dangerous consequences of Ethiopia's move.
Witnesses told AFP on November 19 that convoys of lorries and hundreds of Ethiopian troops crossed in south and central Somalia. Addis Ababa has denied its forces have crossed into the war-torn nation.
Some 250,000 people in south and central Somalia face imminent starvation, the UN report added, despite massive international efforts to get emergency aid out to critically affected regions.
The Al-Qaeda linked Shebab are now battling Kenyan forces in the south, Ugandan and Burundian African Union forces in Mogadishu, and face Ethiopian troops in the west.
Although the UN last week downgraded the number of famine zones by half, reclassifying three regions at emergency levels, the humanitarian crisis in central and southern Somalia remains the worst in the world.
Somalia's neighbours have recently renewed efforts to restore stability there after two decades of chaos, with Nairobi last week saying it was willing to deploy troops for the African Union force protecting the Somali government.
Ethiopia pulled out its soldiers from Somalia in 2009 after a two-year invasion that defeated an Islamist movement, but the group's military wing, the Shebab, regrouped to battle the troops and have waged a bloody war since.
Ugandan and Burundian soldiers making up the 9,700-strong AU force have been battling the Shebab in the capital Mogadishu since deploying in 2007.
Ethiopia has said the decision on whether it will send troops to Somalia will be taken Friday at a heads of state meeting in Addis Ababa of the regional body, the Inter-Governmental Authority on Development.