On Monday, the Russian defence ministry said "dozens of Syrians" were summarily executed in east Aleppo by rebels. "And this, it seems, is only the beginning", Sputnik cited him as saying.
Konashenkov said some of the bodies have been mutilated and some had gunshot wounds.
He added that seven large ammunition depots, enough to arm several infantry battalions, were discovered in Aleppo.
Iran's President Hassan Rouhani and his Russian counterpart Vladimir Putin both congratulated Assad on the reclaiming of Syria's second city from the rebel forces.
Syrian President Bashar al Assad told Russia on Sunday he was saddened by the crash of a Russian military plane on its way to Syria but the countries' fight against Islamist militants would not be affected.
Russian and Syrian jets also launched heavy strikes on rebel-held parts of western and southern parts of rural Aleppo. The evacuees have been taken to rebel-held territory in the countryside west of Aleppo and in Idlib province.
The Syrian Army took the last rebel-held enclaves last week, as rebels and civilians were evacuated.
Christians celebrated Christmas in Aleppo for the first time in four years with the city now under full control of government forces.
Regaining Aleppo represents a momentous victory for President Bashar Assad and a crushing defeat for Syria's United States and Saudi financed opposition which will struggle to forge a way forward.
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.