At least 20 people have been killed in southern Somalia day in clashes between militia from rival clans fighting over land, officials and witnesses said Thursday.

Tensions between fighters from the Owrmale and Majerten clans some 30 kilometres outside the southern port city of Kismayo, have been rising in recent weeks.

"The fighting intensified today and 20 people from the two sides were killed and dozen others including civilians wounded. This is horrible situation which needs to be stopped," Abdikarin Mohamed, a local government official from the area said on phone.

“The dead bodies are strewn in the battle zone and civilians are fleeing as the fighting (which) affected several villages. We have been informed twenty people died and more than that were wounded during the past three days," said Adan Jama, a local elder in Kismayo.

Somalia President Mohamed Abdullahi Farmaajo called on both sides to show restraint and end the bloodshed. "I call on the brotherly people who are fighting in the western Kismayo to stop the bloodshed urgently and unconditionally," The president said in a statement published by national news agency SONNA. 

"It is unfortunate today people are fighting within themselves instead of uniting to fight Al-Shabaab terrorists and liberate their territories," he added, referring to the Al-Qaeda linked Islamists who carry out regular attacks in the country. Intra and inter-clan clashes are common in Somalia, many relating to land disputes and water resources.