A U.S. drone airstrike in Somalia on Tuesday killed at least six civilians, including a 13-year-old boy, according to a Somali lawmaker, raising further questions about the extent of civilian casualties from U.S. military operations.

The U.S. African Command airstrike in the town of Janale in the lower Shabelle region killed at least six unarmed civilians who were traveling to the capital Mogadishu, Mahad Dhoore, a lawmaker from the Southwest state, told local media on Thursday.

"The U.S. African Command (Africom) airstrike hit a minibus carrying unarmed innocent civilians in Janale," Dhoore was quoted as saying.

The six civilians killed by the U.S. airstrike include a 13-year-old who was traveling with his family, he added.

Africom released a statement saying that the airstrike killed five al-Shabab terrorists, adding that it had taken measures to avoid civilian casualties.

"While we currently assess that this airstrike injured no civilians, we are aware of social media reports alleging civilian casualties resulting from this strike. U.S. Africa Command complies with the law of armed conflict and takes all feasible precautions during the targeting process to minimize civilian casualties and other collateral damage," said Africom in a statement.

It was the 26th airstrike by the U.S. in the Horn of Africa nation in only 69 days.

International rights group Amnesty International released a report a year ago alleging U.S. strikes were killing civilians. The report said 14 civilian had been killed in just five air strikes between 2017 and 2018. Africa Command initially denied the allegation but later concluded that two civilians died in a 2018 strike.

Somalia has been at war since 1991, when warlords in the Horn of Africa nation overthrew a dictator and turned on each other.