A statement issued by the transitional government in Somali last week said al-Shabaab was fractured because of an emerging rift between top leaders. The government said it was able to take positions from the al-Qaida affiliate because of the divisions.
"These gains come amidst reports that the Al-Shabaab's second in command has withdrawn his forces from (Mogadishu) as rifts within the extremist group deepen in the wake of the failed Ramadan offensive," CNN International quoted the statement as saying.
Abdirasaq Qaylow, an official in the Somali information ministry, said government forces were able to repel militant attacks last week.
Al-Shabaab leader Abu Zubayr reportedly pulled his troops out of the Somali capital Mogadishu following a dispute with his military commander Mukhtar Robow.
Robow, however, shrugged off the allegations as "baseless propaganda" distributed by AU peacekeepers in Somalia.
Al-Shabaab is trying to set up an Islamist government in Somalia as it wages war against U.N. and AU peacekeepers in the country. The transitional government, whose mandate expires next year, controls only a tiny portion of the capital.