Russia's Defense Ministry said on Monday that its troops had found mass graves in Syria's Aleppo with bodies showing signs of torture and mutilation.
Dozens of bodies have been uncovered, according to Ministry spokesman Maj. Gen. Igor Konashenkov. He said some bore gunshot wounds.
While the Syrian war is now largely fought with mortars, tanks, and air power, death has come at close quarters as well. Human rights observers and the media have recorded numerous examples of massacres and organized torture, perpetrated by the government, opposition, and the Islamic State group.
The Russian Air Force has helped Syrian President Bashar Assad and its allies to capture Aleppo, Syria's largest city, after weeks of a siege. Russia has since dispatched military police to the city.
Konashenkov also accused rebels, who controlled eastern Aleppo before they were pushed out earlier this month, of laying multiple booby traps and mines across town, endangering the civilian population.
The Britain-based Syrian Observatory for Human Rights, which gathers information on the conflict through local contacts, said on Sunday that at least 63 Syrian soldiers and militiamen had been killed by such booby traps in east Aleppo since the government took control of it from rebels last Thursday. The Observatory said the victims were a mix of demining personnel and soldiers or militiamen looting the districts.
As Russian and Syrian forces secured and consolidated eastern Aleppo, Syrian president Bashar Assad was showing signs of increasing confidence in his position.
On Sunday, Assad visited a Christian orphanage near the capital Damascus to mark Christmas.
Photographs posted on the Syrian presidency's Facebook page showed Assad along with his wife, Asma, standing with nuns and orphans in the Damascus suburb of Sednaya.
In the northern city of Aleppo, Christians celebrated Christmas for the first time in four years with the country's largest city now under full control of government forces.
The rebel withdrawal from east Aleppo last week marked Assad's biggest victory since Syria's crisis began in 2011.
Christians, one of the largest religious minorities at about 10 percent of Syria's pre-war 23 million-strong population, have tried to stay on the sidelines of the conflict. However, the opposition's increasingly outspoken Islamism has kept many leaning toward Assad's government.