OCHA made the statement based on the information provided by the non-governmental organisations (NGOs) in Gaalkacyo, Somalia's Mudug region, where the clashes had happened, Xinhua quoted UN spokesman Stephane Dujarric as saying on Monday.
"More than 30 people are estimated to have been killed," said the spokesman.
"Local NGOs are providing mobile health care, water and sanitation services."
Renewed clashes between a militia affiliated to Galmudug and Puntland forces have been reported from Galkayo on Saturday morning, news reports said, adding that the fighting broke out after the militia attacked the base of the Puntland forces in the northern parts of Galkayo.
The standoff, which began a week ago, has seen many residents flee the town's affected areas for fear of being caught in the crossfires, the reports said.