"Our estimate is that since the end of major combat, [late April-early May], 16,000 to 17,000 families have returned to the city," said a civil society source involved in assisting the returnees.
The United Nations Refugee Agency (UNHCR) put the number of returnees at 90,000 or nearly a quarter of the hundreds of thousands of people who fled, adding that insecurity was preventing more returns.
Aid workers estimate that about 400,000 people have fled Mogadishu since February to seek shelter in other regions of the country.
"Many are staying in houses that are partially destroyed, with no roofs, and their belongings looted," the source said, adding that the situation was being exacerbated by the escalation of violence in the city.
The end of major combat operations by Ethiopian-backed government forces against insurgents, has seen a number of roadside bombs and hit-and-run attacks. "Last week was the worst, with almost two or three attacks a day," said a local journalist.
The insecurity had also affected traders. "Business activity has come to a complete stop in some neighbourhoods, such as the SOS hospital area, and the Huriwa area [north Mogadishu]," said the journalist.
"We are appealing to agencies to find a way of reaching these people," a civil society source said. Some of the returnees, she added, were going back to the camps because they at least received some assistance there.
The most pressing need is shelter material and medical aid to help people weakened by months without food or water. "We need help in all areas, but plastic sheeting, food and medical help are most urgently needed," she added.
The United Nations World Food Programme (WFP) distributed 557Mt of food in May to 25,000 people in the city. "These are people who have returned to Mogadishu or those who stayed and are considered vulnerable," WFP spokesman Peter Smerdon said.
Distributions were carried out "relatively smoothly", but the general insecurity in Mogadishu was "making it more difficult" to deliver aid, said Smerdon.
The UN Office for the Coordination of Humanitarian Affairs (OCHA) said that, to date, 366,000 of those displaced since February had been provided with food and supplies such as shelter and household items by UN agencies and their partners.
OCHA voiced particular concern, however, over the prevalence of acute watery diarrhoea, which has killed nearly 1,000 people, and the fact that some areas affected by the outbreak remained inaccessible.