Delay announced as UN says three new regions are “famine zones” and all regions in country’s south are vulnerable.
Abdirahman Omar Osman, a government spokesman, said on Saturday that al-Shabab was retreating from the city, calling it a “golden victory for the Somali people”.
He said government forces have begun deploying cautiously in the pockets of the city previously under al-Shabab control.
The government is urging city residents who fled their homes to return, promising the military will spare no effort in securing their areas.
Ali Mohamed Rage, an al-Shabab spokesman, told a local radio station that the withdrawal was aimed to enable a counter-attack, saying there would be no pull out from other regions of southern Somalia.
He insisted that the move is not a retreat, but rather a change of military tactics toward guerrilla warfare.
Witnesses said convoys of al-Shabab vehicles – open-top 4x4s mounted with machine guns – headed south from Mogadishu towards the al-Shabaab-controlled town of Baidoa, 250km southwest of the capital.
Al Jazeera’s Peter Greste visited a former al-Shabab building in Mogadishu, which he described as “nothing more than an abandoned shell with a few bits of grafitti around it”.
“It sounds like they are planning to continue fighting as a guerrilla force,” our correspondent said. “Though it appears weakened, it may still have the capacity to wage a guerrilla campaign here, and that would be a very difficult thing for the African Union troops and the government to defend against.”
Al-Shabab, which controls much of the south of the country – where the famine is most severe – says the UN is exaggerating the humanitarian crisis, and has banned most aid groups from operating there.
But al-Shabab has been unable to stem the flow of tens of thousands of hungry people moving out of their areas of control in search of food.
On Friday, at least seven Somalis, among them refugees, were killed in a firefight in Mogadishu after troops and residents looted vehicles carrying food meant for famine victims, witnesses say.
The witnessess said government troops fired shots and fought among themselves as they looted maize and oil in the Somali capital.
One witness said he saw a soldier killed and dozens of refugees wounded at Badbaado camp, home to about 30,000 refugees.
“At least 10 people died and 15 others were wounded,” Aden Kusow, himself a refugee, told the Reuters news agency from Badbaado camp.
“Seven of those died in the camp. The other three died outside as they fled. Most of those who died are refugees.”
About 100,000 refugees have reached Mogadishu in the last two months, hoping to escape the brunt of the worst drought to hit the Horn of Africa in decades.
Millions at risk
News of the firefight came as Ahmet Davutoglu, Turkey’s foreign minister, called for the 57-nation Organisation of the Islamic Conference (OIC) to hold an emergency meeting on the situation in Somalia.
Mapping the spread of the Somalia famine
The call for the meeting, which would also deal with the risks that the famine poses to other African countries, follows the postponement until August 25 of an African Union conference on Somalia.
Up to 3.7 million Somalis are at risk of starvation, the majority of them in the south of the country, according to the UN food arm, Food and Agriculture Organisation (FAO).
US officials say that the famine in Somalia has killed more than 29,000 children in the last 90 days.
The FAO said that famine was likely to spread across all regions of Somalia’s south in the next four to six weeks.
Famine, as defined by the UN, refers to situations when at least 20 per cent of households face food shortages so severe that they are unable to cope with it and more than two people out of 10,000 people die daily.
About 450,000 people live in Somalia’s famine zones, according to Grainne Moloney, chief technical adviser for the UN’s Food Security and Nutrition Analysis Unit at FAO-Somalia.