Somalia's militant Islamist group al-Shabab has shot dead execution-style three men.

It accused two of the men of working for the army. The third man killed was an elderly clan leader who helped choose candidates for the 2016 parliamentary elections.

The killings took place in front of a crowd in Mubarak village in southern Somalia, media linked to al-Shabab reported.

The militants, who are affiliated to al-Qaeda, control much territory in rural areas of Somalia, and are fighting to overthrow the UN-backed government.

The militants are known for killing suspected informers, including those accused of spying for US and other foreign intelligence agencies.