The toll of two civilians deaths, from an April 2018 strike, is still far lower than the number investigators from Amnesty International believe have been killed.

The rights group last month reported 14 civilians had been killed from only five airstrikes they had examined, out of a total 110 missile blasts.

But the admission of deaths by US force marks a notable shift in a previous blanket denial of any civilian killings.

US strikes, which included missiles fired by manned aircraft as well as drones, targeted Somalia's Al-Qaeda linked jihadist insurgents, Al-Shabaab.

Following Amnesty's claims in March, the US Africa Command, AFRICOM, said it killed over 800 people in a total of 110 airstrikes in Somalia since April 2017, but insisted every death was that of a "terrorist."

On Friday, however, the US military said in a statement that they had now found two civilians had been killed in an airstrike last year, in Somalia's central El Burr regin.

"An April 1, 2018 airstrike killed two civilians," the statement read. At the time, on April 2, 2018, the US had said no civilians were killed, but that five Al-Shabaab had died. On Friday, it said four Shabaab fighters died.

No further details of the civilians killed by the US missiles were given/

The civilian deaths had not been recorded due to a to a "reporting error", the statement said, but were revealed after a military review was ordered "due to a recent increase in airstrikes and continued interest by Amnesty International and Congress on civilian casualties."

US strikes in Somalia surged in April 2017, after President Donald Trump declared southern Somalia an "area of active hostilities", Amnesty said.

The rate of airstrikes has also risen sharply. The 110 attacks the US said it has carried out since April 2017 includes 28 airstrikes in 2019 alone, compared to 47 in all of 2018, and 35 in 2017.

Amnesty warned that some attacks "may amount to war crimes."

The Shabaab have been waging an insurgency against Somalia's foreign-backed government for over a decade, and while it has lost ground, continues to stage deadly attacks.