Minab, Iran - Human Rights Watch has called for the US and Israel's deadly attack on an Iranian elementary school late last month to be investigated as a war crime.

On February 28, at least 175 people – many of them children – were killed when missiles fell on the Shajareh Tayyebeh Primary School in the town of Minab in southern Iran. The massacre came alongside wider US and Israeli strikes across the country.

President Donald Trump has sought to blame Iran for the strike on the school, without providing evidence.

Analyses by CNN and The New York Times found the US was most likely responsible for the attack. Two US officials told Reuters on condition of anonymity that military investigators believed the same.

HRW has since reviewed videos and photos on social media, satellite images, statements by the Iranian Red Crescent Society and US, Israeli, and Iranian government officials, as well as independent media reports on the attack.

The organization found "the attack was carried out by highly accurate, guided munitions, rather than errant weapons whose guidance or propulsion systems failed or were otherwise disrupted and randomly struck the area."

"A prompt and thorough investigation is needed into this attack, including if those responsible should have known that a school was there and that it would be full of children and their teachers before midday," said Sophia Jones, an open source researcher with HRW's Digital Investigations Lab.

"Those responsible for an unlawful attack should be held to account, including prosecutions of anyone responsible for war crimes."

HRW found that the school was located on the interior border of an Islamic Revolutionary Guard Corps Naval Forces compound, but that it had its own entrance and was separated from the rest of the compound by an inner wall.

"The school's location within the IRGC Naval Force's compound did not, in and of itself, make the school a legitimate target. The school was in use, and children were in attendance on the day of the attack," HRW said.

"Human Rights Watch found no evidence that would indicate that the school was being used for military purposes, though researchers were not able to speak to witnesses of the strikes, families of those killed, or other informed sources."

HRW said the laws of war bar attacks on military targets in cases in which the anticipated harm to civilians and civilian objects is disproportionate to the military gain.

The organization is calling for both an independent investigation into the attack, and for the US to assess its responsibility and make the findings public.

"Allies of the US and Israel should insist on accountability for the Shajareh Tayyebeh school attack and for an end to attacks on civilian infrastructure in all of their operations across the region, before more civilians, including children, are unlawfully killed," Jones insisted.