Several international human rights groups condemned the U.S.-led coalition for not acknowledging their role in the killings of large number of civilians during anti-Daesh operations in Raqqa, northeastern Syria.

"The US-led coalition's ongoing failure to admit to, let alone adequately investigate, the shocking scale of civilian deaths and destruction it caused in Raqqa is a slap in the face for survivors," Amnesty International was quoted as saying by Agence France-Presse (AFP.)

In October last year, the Syrian Democratic Forces (SDF), which is predominantly led by the PKK terrorist organization's Syrian wing, the People's Protection Units (YPG), expelled Daesh from Raqqa, the terrorist organization's de-facto Syrian capital, backed by air strikes by the U.S.-led coalition.

The coalition has been fighting Daesh in Syria and neighboring Iraq since 2014. Thousands of people were killed in the battle to retake Raqqa. The dead were buried quickly in mass graves or left under the rubble.

Amnesty International also said last week that the destruction of Raqqa was "shocking" and thousands of bodies have yet to be exhumed, during a press conference in the Lebanese capital of Beirut. The organization added that 2,521 bodies from the battle for Raqqa have been recovered in the city, the majority of whom were killed by coalition airstrikes.

"Eighty percent of the city is basically in ruins and that applies to schools, to hospitals, to private homes," Amnesty's research director Anna Neistat told AFP after a visit to the region. If the U.S.-led coalition "had the money to bring the city to ruins, if they had the money to carry out this very expensive military campaign, it is absolutely unbelievable that they do not provide enough resources to take responsibility for its consequences," said Neistat.

Previously, in June, Amnesty International said that the U.S.-led military campaign killed hundreds of civilians in indiscriminate bombing, amounting to possible war crimes.

Amnesty International is not the only nongovernmental organization (NGO) that is worried about the civilians' conditions in Raqqa and condemn U.S. for its actions in the region. In July, Human Rights Watch said that Raqqa has "at least nine mass graves, each one estimated to have dozens, if not hundreds, of bodies, making exhumations a monumental task."

In April, on the other hand, the U.N. said that it has conducted its first humanitarian mission to Raqqa since Daesh has been cleared from the province, warning that returning civilians face enormous risks, as it is littered with unexploded devices.

The coalition has acknowledged direct responsibility for more than 1,100 civilian deaths in Syria and Iraq since 2014, but rights groups put the number killed much higher.

The Syrian Observatory for Human Rights, a U.K.-based war monitor, says coalition strikes in Syria alone have killed more than 3,300 civilians. Syria's war has killed more than 360,000 people since it erupted in 2011 with the brutal repression of anti-regime protests.