Somalia's embattled government offered an open amnesty on Tuesday to Islamist Shebab fighters after the rebels made a surprise withdrawal from the famine-struck capital over the weekend.
The Al-Qaeda affiliated insurgents have waged a bloody war since 2007 to topple the Western-backed transitional government, which they had hemmed in to a portion of Mogadishu.
"We offer an amnesty -- put down your weapons and your guns, and come and join the people and your society," said Abdirahman Osman, a spokesman for the transitional government.
"For those who have been misled by the senior commanders, now is the time to end the war."
The extremist fighters, who had controlled around half of Mogadishu, abandoned their positions on Saturday but some units remained active within the capital.
Fighting was reported as rebel remnants clashed with African Union-backed government troops after the pullout.
Sporadic gunfire was heard in the city on Tuesday morning, according to an AFP correspondent.
Government officials celebrated the hardline rebel pullout but the Shebab said it was merely "a change of military tactics."
The 9,000-strong AU force (AMISOM) and government troops have meanwhile reinforced their hold over former rebel positions in an effort to allow more aid into the famine-struck capital on Tuesday.
"The extremists have been preventing the provision of food to hungry Somalis and this has opened up the opportunity to help many more people," said Boubacar Gaoussou Diarra, the AU special representative to Somalia, in a statement released late Monday.
AMISOM however warned people intending to return to former Shebab-controlled areas of the "high possibility" of "roadside bombs and pockets of remaining extremist fighters," Diarra said.
The UN Coordination of Humanitarian Affairs (OCHA) said it was assessing how the rebel withdrawal would open aid group access to the war-torn city, to which about 100,000 people have fled in the past two months to escape extreme drought.
"Although it is too early to know what the impact on the overall situation is, humanitarian actors are assessing the ability to operate and/or scale up activities," it said a statement Tuesday.
The United Nations has officially declared famine in Somalia for the first time this century, including in Mogadishu and four southern Somali regions.
"Famine... is expected to spread across all regions of the south in the coming four to six weeks," OCHA warned.
"Cases of acute watery diarrhoea are increasing across Somalia," it added.
Much of southern Somalia -- including most of the regions declared to be in famine -- is still controlled by the Shebab rebels.
The UN's food monitoring unit has described Somalia as facing the most severe humanitarian crisis in the world and Africa's worst food security crisis since the country's 1991-1992 famine.
Parts of Ethiopia, Djibouti, Kenya and Uganda have also been hit by the Horn of Africa's worst drought in decades.