Heavy fighting has taken place between rival factions of Somalia's militant Islamist group al-Shabab near the key coastal town of Brava, witnesses say.
Six militants, including two foreigners, were killed in the gun-battle at dawn, they told the BBC.
Al-Shabab denied there had been any fighting within its ranks.
If confirmed, these would be the first clashes between rival factions of the al-Qaeda linked group since it launched an insurgency in 2006.
On Wednesday, at least 15 people were killed in an attack by al-Shabab on the UN offices in the capital, Mogadishu.
Its fighters detonated a car bomb, before engaging in a fierce battle with security guards in the UN compound.
Residents say Brava is tense following the gun-battle between rival factions on the outskirts of the town, some 220km (140 miles) down the coast from Mogadishu.
Al-Shabab has turned Brava into one of its main bases after losing control of many other towns and cities to African Union (AU) and government troops.
The exact cause of the clashes is not known, but there has been a long-running power struggle within al-Shabab involving its leader Ahmed Abdi Godane and ex-spokesman Muktar Ali Robow, analysts say.
Mr Robow is said to be more moderate than Mr Godane, and opposes links with al-Qaeda, they say.
However, al-Shabab spokesman Ali Dheere dismissed reports of the fighting in Brava as "propaganda" and "lies".
The group was united, he added.
Al-Shabab, which means "The Youth", is fighting to create an Islamic state in Somalia.
It was formed in 2006 as a radical offshoot of the now-defunct Union of Islamic Courts, which at the time controlled Mogadishu and many southern and central areas.
Some 18,000 African Union troops are in Somalia supporting the government of President Hassan Sheikh Mohamud who was elected by MPs last September.
His administration is the first one in more than two decades to be recognised by the US and the International Monetary Fund (IMF).