Latest fighting between government forces and the Al-Shabaab militia have displaced more than 100 000 people across Somalia since the start of the year, says UNHCR.

The UN agency said at least 33,000 are from war-battered Mogadishu while the remaining figure is mainly from south central Somalia.

"We are especially concerned about the safety and well-being of some 8,300 people who, without any means to get out of Mogadishu, remain displaced within the capital," a UNHCR spokesman, Andrej Mahecic, told journalists in Geneva.

"As the fighting rages on, aid agencies cannot access and assist these extremely vulnerable IDPs [internally displaced people]," he added.

The affected areas include five districts in Mogadishu which are Karan, Yaqshid, Abdiasiis, Bondhere iyo Shibbis. Fleeing residents told Garowe Online that they could not stand the sound of mortars and daily gunfire with much of the fear coming from the launch of the much awaited government offensives.

"We could not stand the sound and shelling of mortars. We are leaving our homes to safe areas because the warring sides are not caring for us," said Raho Omar, a mother of four who fled Karan district.

The refugee agency said the large portion of the displaced have moved to Afgooye corridor, a stretch of road some 30 kilometres west of the capital while thousands have fled to other areas with some crossing the border into Kenya.

The UNHCR also raised concerns over the situation in overcrowded Dadaab refugee complex in northern Kenya, which recorded 10,000 new arrivals since February.

The complex, which was initially meant to hold at least 90,000 people, is currently hosting more than 270,000.

The UN estimates that more than 1.4 million IDPs are languishing inside Somalia while over 560,000 Somalis live as refugees in neighboring countries.