The incident could anger the local population in the run-up to an offensive against al Shabaab rebels in the southern port of Kismayu in a final push by African nations to stabilise the country.

The Kenya Defence Force (KDF) said the incident happened on Sunday in the Jubba region after several people approached a KDF defensive position.

"A KDF soldier allegedly opened fire killing six people. The soldier was immediately disarmed and has since been put on guarded seclusion," it said in a statement.

It said the matter was being investigated by AMISOM force commanders, KDF and the Somali army, who would later release their findings.

"The findings will duly be respected and appropriate action taken," KDF said.

Somalia has made progress in the past year in battling an Islamist insurgency and elected a new president earlier this month, but it faces security challenges, mainly bomb attacks carried out by al Shabaab.