Continuing fighting in Somalia's capital, Mogadishu, has caused the displacement of at least 22,000 more civilians and forced relief agencies to curtail their operations in the war-scarred city during the past 12 days, the United Nations reported on Friday.

Nearly 14,000 of those displaced are believed to have left the city, while another 7,200 joined 366,000 other internally displaced persons in the Afgooye corridor, a 30-kilometre stretch of road west of Mogadishu that has been described as one of the world's most densely populated settlements of homeless people.

An estimated 8,700 people moved to other relatively safer areas of Mogadishu, the UN Office for the Coordination of Humanitarian Affairs (OCHA) said, quoting figures provided by the UN refugee agency UNHCR.

Clashes pit forces of Somalia's Transitional Federal Government (TFG), who are backed by African Union troops, against Islamist insurgents seeking to topple the internationally-supported administration. According to OCHA, this week's fighting was one of the heaviest that Mogadishu has experienced this year.