Islamist rebels moved on Friday into a small town on the outskirts of Somalia's capital near a checkpoint manned by Ethiopian troops, sparking fears among residents of renewed fighting.
This week's advance by al Shabaab militants towards the capital Mogadishu is a potential setback for a fledgling U.N.-brokered peace process to end 17 years of conflict in the Horn of Africa nation.
Al Shabaab fighters, who are on Washington's list of foreign terrorist groups, moved into Elasha town overnight, 2 km (1 mile) from Sinkadheer, where Ethiopian troops are based.
Sinkadheer is 15 km (9 miles) south-west of Mogadishu.
"We have been fighting to get peace, we shall defend the people around Elasha and nearby areas from robbers or Ethiopians," said Sheikh Abdirahim Isse Adow, a spokesman for the Islamic Courts Union whose fighters were alongside al Shabaab members in Elasha.
The Islamists, who launched an Iraqi-style insurgency against Somalia's interim government and its Ethiopian military allies two years ago, had briefly occupied Elasha on Thursday.
Al Shabaab has been gaining territory in southern Somalia. In the past week, it has taken control of three towns and briefly occupied three others in south Somalia.
The chaos in Somalia has fuelled instability around the Horn of Africa, caused one of the world's worst humanitarian crises and sparked a rash of piracy in the Gulf of Aden, a crucial shipping lane for trade between Europe and Asia.
On Wednesday, the Islamists seized Merka, a strategic port 90 km (55 miles) southwest of Mogadishu used by the U.N. World Food Programme for food aid deliveries, giving al Shabaab its closest foothold yet to Mogadishu.
Al Shabaab have rejected the U.N.-negotiated pact to set up a power-sharing administration between the government and some moderate opposition figures, and ignored a ceasefire.
Many residents in Elasha have already fled fighting in Mogadishu and were afraid renewed clashes would cut off the supply of food aid.
"We do not know where to evacuate to again if Ethiopian troops and al Shabaab clash around our camps. We have no hope of getting relief food," Alasey Jimcale, a mother-of-four in Elasha, told Reuters. "Mogadishu is not a place to go back to."
Under the U.N.-brokered deal, Ethiopian forces were due to start withdrawing from Mogadishu and other towns later this month. But the Islamist advance may scupper that deadline.