The coalition’s admission last month that it killed 77 more civilians than previously reported was just the “tip of the iceberg”, the rights group said in a statement published on Tuesday.
The probe is needed to understand why civilians were killed and who was responsible, the watchdog said, adding that Raqqa residents deserved justice and compensation.
“Every family I met in Raqqa has one question which was ‘why did the coalition bomb us?’,” said Amnesty’s adviser Donatella Rovera in the statement.
“It is time that the coalition stops being in denial and does the right thing: a proper independent investigation.”
Amnesty also said it believed hundreds of civilians were killed and that the coalition had under-reported the casualties.
There was no immediate comment from the Global Coalition, a group formed by 77 countries whose mission is to degrade and ultimately defeat the Islamic State of Iraq and the Levant (ISIL, also known as ISIS).
The coalition needs to release “meaningful and verifiable information” about how targets in Raqqa were selected and how strikes were carried out, the statement said.
“How can the coalition avoid inflicting high civilian death tolls in the future without accounting for what went wrong?” said Rovera in the statement.
“Nothing can ever bring back the dead or wipe away the unimaginable trauma. The least the Coalition can do right now is provide restorative measures – including compensation and rehabilitation – to victims’ families and survivors.”
Violence in Raqqa
The coalition had initially put the civilian death toll at 32 in the campaign in Raqqa, the de-facto capital of ISIL.
But an Amnesty investigation published in June and based on testimony collected from Raqqa residents prompted the coalition to add 77 civilians to the death toll, 49 of whom Amnesty said were women and children killed in the aerial bombardment.
Amnesty has also criticised the coalition’s monthly reports, which offer only generalities about the strikes.
“Such short-hand explanations are woefully inadequate,” it said.
.@CJTFOIR dismissed @amnesty's report re civilians killed by #USA-led Coalition's bombardments in #Raqqa ; said we are naive & misinformed, but now admits responsibility for the cases we reported. But there are many more victims. Coalition must come clean https://t.co/dU6WM1EHUj pic.twitter.com/oKzPZH5Grr
— Donatella Rovera (@DRovera) August 7, 2018
The battle for Raqqa, once a city of 200,000 people, took place over four months in 2017, with the coalition playing a supporting role as the Kurdish-led Syrian forces fought street by street.
The coalition unleashed a series of air strikes and shell fire until the last of the ISIL fighters left Raqqa in October 2017.
The city was left in ruins, civil workers pulled nearly 500 corpses from the rubble in the immediate aftermath and were still finding more months after the fighting.
ISIL has been mostly defeated in Iraq and Syria, though it still controls some small areas in both countries.