Pro-government forces have launched a major offensive from the Somali capital, Mogadishu, to seize territory from al-Shabab Islamist militants.
Some 1,000 soldiers backed up by 20 tanks captured three al-Shabab bases, a senior security official said.
African Union forces backing the government says they have advanced outside the capital for the first time.
Al-Shabab is under attack on several fronts, with troops from Kenya and Ethiopia also gaining ground recently.
Correspondents says this is the biggest joint offensive by the government and the AU force, Amisom, since August 2011.
Troops from Djibouti have recently arrived in Mogadishu to bolster Amisom's 12,000 soldiers, while the AU is asking the UN to approve a further 50% increase in troop numbers.
Al-Shabab controls many southern and central areas of the country.
The al-Qaeda linked group made a "tactical withdrawal" from most of the capital last year but has continued to stage suicide attacks in the city.
It confirmed that the pro-government forces had gained territory but vowed to hit back.