Russia has accused the US-led coalition of bombing the Syrian city of Raqqa "off the face of the earth" during the fight against so-called Islamic State.
Syrian Democratic Forces (SDF) took Raqqa last week and on Sunday said they had taken Syria's largest oilfield.
Pictures suggest much of Raqqa is in ruins, and Moscow compared it to the Allied destruction of the German city of Dresden in World War Two.
The US-led coalition says it tried to minimise risks to civilians.
Russia has itself been accused of committing war crimes for its bombardment of Aleppo last year.
UN war crimes investigators said last week that there had been a "staggering loss of civilian life" in Raqqa.
Syrian activists say between 1,130 and 1,873 civilians were killed and that many of the civilian casualties were the result of the intense US-led air strikes that helped the SDF, an alliance of Kurdish and Arab militias, advance.
A Russian defence ministry spokesman said the ruins evoked the destruction of Dresden.
"Raqqa has inherited the fate of Dresden in 1945, wiped off the face of the earth by Anglo-American bombardments," Maj Gen Igor Konashenkov said.
He said the West now appeared to be hurrying to send financial aid to Raqqa as a way of covering up evidence of its crimes.
The US-led coalition said it had adhered to strict targeting processes and procedures aimed to minimise risks to civilians.
The SDF declared victory in Raqqa last week after a four-month battle to retake the city from IS, which had ruled it for three years.
They say they have since taken the al-Omar oilfield, a significant source of revenue of the militants.
The fight against the militants is now focussed on their last stronghold in Syria's eastern province of Deir al-Zour.
The Syrian army backed up by Russian airpower and Iranian militias is also attacking the extremist group.