An investigation into a 2019 strike by US forces in Syria that killed numerous civilians found no violations of policy or wanton negligence, the Pentagon said Tuesday, according to AFP.

The internal US Army investigation focused on an operation by a special US force operating in Syria which launched an airstrike on an Islamic State bastion in Baghouz on March 18, 2019.

US Defense Secretary Lloyd Austin ordered the review of the 2019 strike after a New York Times report said that the strike killed up to 64 women and children and was covered up by the US military.

The Times report had said a US legal officer "flagged the strike as a possible war crime" and that "at nearly every step, the military made moves that concealed the catastrophic strike."

The final report of the investigation rejected that conclusion Tuesday, saying that the US ground force commander for the anti-Islamic State coalition received a request for air strike support from Syrian Democratic Forces fighting the extremists.

The commander "received confirmation that no civilians were in the strike area" and authorized the strike.

However, they later found out there were civilians at the location.

"No Rules of Engagement or Law of War violations occurred," the investigation said, according to AFP.

In addition, the commander "did not deliberately or with wanton disregard cause civilian casualties," it said.

The report said that "administrative deficiencies" delayed US military reporting on the strike, giving the impression that it was being covered up.